Renaming project because of cocoapods name clash with HardcoreData :(

CoreStore/Convenience Helpers/NSManagedObject+Convenience.swift

@@ -0,0 +1,49 @@
+//
+//  NSManagedObject+Convenience.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - NSManagedObject
+
+public extension NSManagedObject {
+    
+    public func accessValueForKVCKey(KVCKey: KeyPath) -> AnyObject? {
+        
+        self.willAccessValueForKey(KVCKey)
+        let primitiveValue: AnyObject? = self.primitiveValueForKey(KVCKey)
+        self.didAccessValueForKey(KVCKey)
+        
+        return primitiveValue
+    }
+    
+    public func setValue(value: AnyObject?, forKVCKey KVCKey: KeyPath) {
+        
+        self.willChangeValueForKey(KVCKey)
+        self.setPrimitiveValue(value, forKey: KVCKey)
+        self.didChangeValueForKey(KVCKey)
+    }
+}

CoreStore/CoreStore.h

@@ -0,0 +1,30 @@
+//
+//  CoreStore.h
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+#import <CoreData/CoreData.h>
+
+FOUNDATION_EXPORT double CoreStoreVersionNumber;
+FOUNDATION_EXPORT const unsigned char CoreStoreVersionString[];
+

CoreStore/CoreStore.swift

@@ -0,0 +1,78 @@
+//
+//  CoreStore.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import CoreData
+import GCDKit
+
+
+/**
+Okay, okay. This one's shorter.
+*/
+public typealias HCD = CoreStore
+
+
+// MARK: - CoreStore
+
+/**
+`CoreStore` is the main entry point for all other APIs.
+*/
+public enum CoreStore {
+    
+    // MARK: Public
+    
+    /**
+    The default `DataStack` instance to be used. If `defaultStack` is not set before the first time accessed, a default-configured `DataStack` will be created.
+    
+    Changing the `defaultStack` is thread safe, but it is recommended to setup `DataStacks` on a common queue (e.g. the main queue).
+    */
+    public static var defaultStack: DataStack {
+        
+        get {
+        
+            self.defaultStackBarrierQueue.barrierSync {
+        
+                if self.defaultStackInstance == nil {
+        
+                    self.defaultStackInstance = DataStack()
+                }
+            }
+            return self.defaultStackInstance!
+        }
+        set {
+            
+            self.defaultStackBarrierQueue.barrierAsync {
+                
+                self.defaultStackInstance = newValue
+            }
+        }
+    }
+    
+    
+    // MARK: Private
+    
+    private static let defaultStackBarrierQueue = GCDQueue.createConcurrent("com.coreStore.defaultStackBarrierQueue")
+    
+    private static var defaultStackInstance: DataStack?
+}

CoreStore/Fetching and Querying/BaseDataTransaction+Querying.swift

@@ -0,0 +1,271 @@
+//
+//  BaseDataTransaction+Querying.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - DataTransaction
+
+public extension BaseDataTransaction {
+    
+    // MARK: Public
+    
+    /**
+    Fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the first `NSManagedObject` instance that satisfies the specified `FetchClause`s
+    */
+    public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchOne(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the first `NSManagedObject` instance that satisfies the specified `FetchClause`s
+    */
+    public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchOne(from, fetchClauses)
+    }
+    
+    /**
+    Fetches all `NSManagedObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: all `NSManagedObject` instances that satisfy the specified `FetchClause`s
+    */
+    public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchAll(from, fetchClauses)
+    }
+    
+    /**
+    Fetches all `NSManagedObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: all `NSManagedObject` instances that satisfy the specified `FetchClause`s
+    */
+    public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchAll(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the number of `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchCount(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the number of `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchCount(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s
+    */
+    public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchObjectID(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s
+    */
+    public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchObjectID(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to fetch from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    /**
+    Deletes all `NSManagedObject`'s that satisfy the specified `DeleteClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: deleteClauses a series of `DeleteClause` instances for the delete request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number of `NSManagedObject`'s deleted
+    */
+    public func deleteAll<T: NSManagedObject>(from: From<T>, _ deleteClauses: DeleteClause...) -> Int? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to delete from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.deleteAll(from, deleteClauses)
+    }
+    
+    /**
+    Deletes all `NSManagedObject`'s that satisfy the specified `DeleteClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: deleteClauses a series of `DeleteClause` instances for the delete request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number of `NSManagedObject`'s deleted
+    */
+    public func deleteAll<T: NSManagedObject>(from: From<T>, _ deleteClauses: [DeleteClause]) -> Int? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to delete from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.deleteAll(from, deleteClauses)
+    }
+    
+    /**
+    Queries aggregate values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to query from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.queryValue(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Queries aggregate values or aggregates as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to query from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.queryValue(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Queries a dictionary of attribute values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to query from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.queryAttributes(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Queries a dictionary of attribute values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: [QueryClause]) -> [[NSString: AnyObject]]? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to query from a \(typeName(self)) outside its designated queue.")
+        
+        return self.context.queryAttributes(from, selectClause, queryClauses)
+    }
+}

CoreStore/Fetching and Querying/Concrete Clauses/From.swift

@@ -0,0 +1,158 @@
+//
+//  From.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - From
+
+/**
+A `Form` clause binds the `NSManagedObject` entity type to the generics type system.
+*/
+public struct From<T: NSManagedObject> {
+    
+    // MARK: Public
+    
+    public init(){
+        
+        self.findPersistentStores = { _ in nil }
+    }
+    
+    public init(_ entity: T.Type) {
+        
+        self.findPersistentStores = { _ in nil }
+    }
+    
+    public init(_ configurations: String...) {
+        
+        self.init(configurations: configurations)
+    }
+    
+    public init(_ configurations: [String]) {
+        
+        self.init(configurations: configurations)
+    }
+    
+    public init(_ entity: T.Type, _ configurations: String...) {
+        
+        self.init(configurations: configurations)
+    }
+    
+    public init(_ entity: T.Type, _ configurations: [String]) {
+        
+        self.init(configurations: configurations)
+    }
+    
+    public init(_ storeURLs: NSURL...) {
+        
+        self.init(storeURLs: storeURLs)
+    }
+    
+    public init(_ storeURLs: [NSURL]) {
+        
+        self.init(storeURLs: storeURLs)
+    }
+    
+    public init(_ entity: T.Type, _ storeURLs: NSURL...) {
+        
+        self.init(storeURLs: storeURLs)
+    }
+    
+    public init(_ entity: T.Type, _ storeURLs: [NSURL]) {
+        
+        self.init(storeURLs: storeURLs)
+    }
+    
+    public init(_ persistentStores: NSPersistentStore...) {
+        
+        self.init(persistentStores: persistentStores)
+    }
+    
+    public init(_ persistentStores: [NSPersistentStore]) {
+        
+        self.init(persistentStores: persistentStores)
+    }
+    
+    public init(_ entity: T.Type, _ persistentStores: NSPersistentStore...) {
+        
+        self.init(persistentStores: persistentStores)
+    }
+    
+    public init(_ entity: T.Type, _ persistentStores: [NSPersistentStore]) {
+        
+        self.init(persistentStores: persistentStores)
+    }
+    
+    
+    // MARK: Internal
+    
+    internal func applyToFetchRequest(fetchRequest: NSFetchRequest, context: NSManagedObjectContext) {
+        
+        fetchRequest.entity = context.entityDescriptionForEntityClass(T.self)
+        fetchRequest.affectedStores = self.findPersistentStores(context: context)
+    }
+    
+    
+    // MARK: Private
+    
+    private let findPersistentStores: (context: NSManagedObjectContext) -> [NSPersistentStore]?
+    
+    private init(configurations: [String]) {
+        
+        let configurationsSet = Set(configurations)
+        self.findPersistentStores = { (context: NSManagedObjectContext) -> [NSPersistentStore]? in
+            
+            return context.parentStack?.persistentStoresForEntityClass(T.self)?.filter {
+                
+                return configurationsSet.contains($0.configurationName)
+            }
+        }
+    }
+    
+    private init(storeURLs: [NSURL]) {
+        
+        let storeURLsSet = Set(storeURLs)
+        self.findPersistentStores = { (context: NSManagedObjectContext) -> [NSPersistentStore]? in
+            
+            return context.parentStack?.persistentStoresForEntityClass(T.self)?.filter {
+                
+                return $0.URL != nil && storeURLsSet.contains($0.URL!)
+            }
+        }
+    }
+    
+    private init(persistentStores: [NSPersistentStore]) {
+        
+        let persistentStores = Set(persistentStores)
+        self.findPersistentStores = { (context: NSManagedObjectContext) -> [NSPersistentStore]? in
+            
+            return context.parentStack?.persistentStoresForEntityClass(T.self)?.filter {
+                
+                return persistentStores.contains($0)
+            }
+        }
+    }
+}

CoreStore/Fetching and Querying/Concrete Clauses/GroupBy.swift

@@ -0,0 +1,82 @@
+//
+//  GroupBy.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - GroupBy
+
+/**
+The `GroupBy` clause specifies that the result of a query be grouped accoording to the specified key path.
+*/
+public struct GroupBy: QueryClause {
+    
+    // MARK: Public
+    
+    /**
+    Initializes a `GroupBy` clause with a list of key path strings
+    
+    :param: keyPaths a list of key path strings to group results with
+    */
+    public init(_ keyPaths: [KeyPath]) {
+        
+        self.keyPaths = keyPaths
+    }
+    
+    /**
+    Initializes a `GroupBy` clause with an empty list of key path strings
+    */
+    public init() {
+        
+        self.init([])
+    }
+    
+    /**
+    Initializes a `GroupBy` clause with a list of key path strings
+    
+    :param: keyPath a key path string to group results with
+    :param: keyPaths a series of key path strings to group results with
+    */
+    public init(_ keyPath: KeyPath, _ keyPaths: KeyPath...) {
+        
+        self.init([keyPath] + keyPaths)
+    }
+    
+    public let keyPaths: [KeyPath]
+    
+    
+    // MARK: QueryClause
+    
+    public func applyToFetchRequest(fetchRequest: NSFetchRequest) {
+        
+        if fetchRequest.propertiesToGroupBy != nil {
+            
+            CoreStore.log(.Warning, message: "An existing \"propertiesToGroupBy\" for the <\(NSFetchRequest.self)> was overwritten by \(typeName(self)) query clause.")
+        }
+        
+        fetchRequest.propertiesToGroupBy = self.keyPaths
+    }
+}

CoreStore/Fetching and Querying/Concrete Clauses/OrderBy.swift

@@ -0,0 +1,143 @@
+//
+//  OrderBy.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+public func +(left: OrderBy, right: OrderBy) -> OrderBy {
+    
+    return OrderBy(left.sortDescriptors + right.sortDescriptors)
+}
+
+
+// MARK: - KeyPath
+    
+public typealias KeyPath = String
+
+
+// MARK: - SortKey
+
+/**
+The `SortKey` is passed to the `OrderBy` clause to indicate the sort keys and their sort direction.
+*/
+public enum SortKey {
+    
+    /**
+    Indicates that the `KeyPath` should be sorted in ascending order
+    */
+    case Ascending(KeyPath)
+    
+    /**
+    Indicates that the `KeyPath` should be sorted in descending order
+    */
+    case Descending(KeyPath)
+}
+
+
+// MARK: - OrderBy
+
+/**
+The `OrderBy` clause specifies the sort order for results for a fetch or a query.
+*/
+public struct OrderBy: FetchClause, QueryClause, DeleteClause {
+    
+    // MARK: Public
+    
+    /**
+    Initializes a `OrderBy` clause with a list of sort descriptors
+    
+    :param: sortDescriptors a series of `NSSortDescriptor`'s
+    */
+    public init(_ sortDescriptors: [NSSortDescriptor]) {
+        
+        self.sortDescriptors = sortDescriptors
+    }
+    
+    /**
+    Initializes a `OrderBy` clause with an empty list of sort descriptors
+    */
+    public init() {
+        
+        self.init([NSSortDescriptor]())
+    }
+    
+    /**
+    Initializes a `OrderBy` clause with a single sort descriptor
+    
+    :param: sortDescriptor a `NSSortDescriptor`
+    */
+    public init(_ sortDescriptor: NSSortDescriptor) {
+        
+        self.init([sortDescriptor])
+    }
+    
+    /**
+    Initializes a `OrderBy` clause with a series of `SortKey`'s
+    
+    :param: sortKey a series of `SortKey`'s
+    */
+    public init(_ sortKey: [SortKey]) {
+        
+        self.init(
+            sortKey.map { SortKey -> NSSortDescriptor in
+                
+                switch SortKey {
+                    
+                case .Ascending(let keyPath):
+                    return NSSortDescriptor(key: keyPath, ascending: true)
+                    
+                case .Descending(let keyPath):
+                    return NSSortDescriptor(key: keyPath, ascending: false)
+                }
+            }
+        )
+    }
+    
+    /**
+    Initializes a `OrderBy` clause with a series of `SortKey`'s
+    
+    :param: sortKey a single `SortKey`
+    :param: sortKeys a series of `SortKey`'s
+    */
+    public init(_ sortKey: SortKey, _ sortKeys: SortKey...) {
+        
+        self.init([sortKey] + sortKeys)
+    }
+    
+    public let sortDescriptors: [NSSortDescriptor]
+    
+    
+    // MARK: FetchClause, QueryClause, DeleteClause
+    
+    public func applyToFetchRequest(fetchRequest: NSFetchRequest) {
+        
+        if fetchRequest.sortDescriptors != nil {
+            
+            CoreStore.log(.Warning, message: "Existing sortDescriptors for the <\(NSFetchRequest.self)> was overwritten by \(typeName(self)) query clause.")
+        }
+        
+        fetchRequest.sortDescriptors = self.sortDescriptors
+    }
+}

CoreStore/Fetching and Querying/Concrete Clauses/Select.swift

@@ -0,0 +1,693 @@
+//
+//  Select.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - SelectResultType
+
+/**
+The `SelectResultType` protocol is implemented by return types supported by the `Select` clause.
+*/
+public protocol SelectResultType { }
+
+
+// MARK: - SelectValueResultType
+
+/**
+The `SelectValueResultType` protocol is implemented by return types supported by the `queryValue(...)` methods.
+*/
+public protocol SelectValueResultType: SelectResultType {
+    
+    static func fromResultObject(result: AnyObject) -> Self?
+}
+
+
+// MARK: - SelectAttributesResultType
+
+/**
+The `SelectValueResultType` protocol is implemented by return types supported by the `queryAttributes(...)` methods.
+*/
+public protocol SelectAttributesResultType: SelectResultType {
+    
+    static func fromResultObjects(result: [AnyObject]) -> [[NSString: AnyObject]]
+}
+
+
+// MARK: - SelectTerm
+
+/**
+The `SelectTerm` is passed to the `Select` clause to indicate the attributes/aggregate keys to be queried.
+*/
+public enum SelectTerm: StringLiteralConvertible {
+    
+    // MARK: Public
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying an entity attribute. A shorter way to do the same is to assign from the string keypath directly:
+    
+        let fullName = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<String>(.Attribute("fullName")),
+            Where("employeeID", isEqualTo: 1111)
+        )
+    
+    is equivalent to:
+    
+        let fullName = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<String>("fullName"),
+            Where("employeeID", isEqualTo: 1111)
+        )
+    
+    :param: keyPath the attribute name
+    :returns: a `SelectTerm` to a `Select` clause for querying an entity attribute
+    */
+    public static func Attribute(keyPath: KeyPath) -> SelectTerm {
+        
+        return ._Attribute(keyPath)
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying the average value of an attribute.
+
+        let averageAge = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.Average("age"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "average(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for querying the average value of an attribute
+    */
+    public static func Average(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "average:",
+            keyPath,
+            As: alias ?? "average(\(keyPath))"
+        )
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for a count query.
+    
+        let numberOfEmployees = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.Count("employeeID"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "count(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for a count query
+    */
+    public static func Count(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "count:",
+            keyPath,
+            As: alias ?? "count(\(keyPath))"
+        )
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying the maximum value for an attribute.
+    
+        let maximumAge = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.Maximum("age"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "max(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for querying the maximum value for an attribute
+    */
+    public static func Maximum(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "max:",
+            keyPath,
+            As: alias ?? "max(\(keyPath))"
+        )
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying the median value for an attribute.
+    
+        let medianAge = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.Median("age"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "max(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for querying the median value for an attribute
+    */
+    public static func Median(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "median:",
+            keyPath, As:
+            alias ?? "median(\(keyPath))"
+        )
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying the minimum value for an attribute.
+    
+        let minimumAge = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.Median("age"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "min(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for querying the minimum value for an attribute
+    */
+    public static func Minimum(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "min:",
+            keyPath,
+            As: alias ?? "min(\(keyPath))"
+        )
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying the standard deviation value for an attribute.
+    
+        let stddevAge = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.StandardDeviation("age"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "stddev(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for querying the standard deviation value for an attribute
+    */
+    public static func StandardDeviation(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "stddev:",
+            keyPath,
+            As: alias ?? "stddev(\(keyPath))"
+        )
+    }
+    
+    /**
+    Provides a `SelectTerm` to a `Select` clause for querying the sum value for an attribute.
+    
+        let totalAge = CoreStore.queryValue(
+            From(MyPersonEntity),
+            Select<Int>(.Sum("age"))
+        )
+    
+    :param: keyPath the attribute name
+    :param: alias the dictionary key to use to access the result. Ignored when the query return value is not an `NSDictionary`. If `nil`, the default key "sum(<attributeName>)" is used
+    :returns: a `SelectTerm` to a `Select` clause for querying the sum value for an attribute
+    */
+    public static func Sum(keyPath: KeyPath, As alias: KeyPath? = nil) -> SelectTerm {
+        
+        return ._Aggregate(
+            function: "sum:",
+            keyPath,
+            As: alias ?? "sum(\(keyPath))"
+        )
+    }
+    
+    
+    // MARK: StringLiteralConvertible
+    
+    public init(stringLiteral value: KeyPath) {
+        
+        self = ._Attribute(value)
+    }
+    
+    public init(unicodeScalarLiteral value: KeyPath) {
+        
+        self = ._Attribute(value)
+    }
+    
+    public init(extendedGraphemeClusterLiteral value: KeyPath) {
+        
+        self = ._Attribute(value)
+    }
+    
+    
+    // MARK: Internal
+    
+    case _Attribute(KeyPath)
+    case _Aggregate(function: String, KeyPath, As: String)
+}
+
+
+// MARK: - Select
+
+/**
+The `Select` clause indicates the attribute / aggregate value to be queried. The generic type is a `SelectResultType`, and will be used as the return type for the query. 
+
+You can bind the return type by specializing the initializer:
+
+    let maximumAge = CoreStore.queryValue(
+        From(MyPersonEntity),
+        Select<Int>(.Maximum("age"))
+    )
+
+or by casting the type of the return value:
+
+    let maximumAge: Int = CoreStore.queryValue(
+        From(MyPersonEntity),
+        Select(.Maximum("age"))
+    )
+
+Valid return types depend on the query:
+
+- for `queryValue(...)` methods:
+    - `Bool`
+    - `Int8`
+    - `Int16`
+    - `Int32`
+    - `Int64`
+    - `Double`
+    - `Float`
+    - `String`
+    - `NSNumber`
+    - `NSString`
+    - `NSDecimalNumber`
+    - `NSDate`
+    - `NSData`
+    - `NSManagedObjectID`
+    - `NSString`
+- for `queryAttributes(...)` methods:
+    - `NSDictionary`
+
+:param: sortDescriptors a series of `NSSortDescriptor`'s
+*/
+public struct Select<T: SelectResultType> {
+    
+    // MARK: Public
+    
+    /**
+    The `SelectResultType` type for the query's return value
+    */
+    public typealias ReturnType = T
+    
+    /**
+    Initializes a `Select` clause with a list of `SelectTerm`'s
+    
+    :param: selectTerm a `SelectTerm`
+    :param: selectTerms a series of `SelectTerm`'s
+    */
+    public init(_ selectTerm: SelectTerm, _ selectTerms: SelectTerm...) {
+        
+        self.selectTerms = [selectTerm] + selectTerms
+    }
+
+
+    // MARK: Internal
+
+    internal func applyToFetchRequest(fetchRequest: NSFetchRequest) {
+        
+        if fetchRequest.propertiesToFetch != nil {
+            
+            CoreStore.log(.Warning, message: "An existing \"propertiesToFetch\" for the <\(NSFetchRequest.self)> was overwritten by \(typeName(self)) query clause.")
+        }
+        
+        fetchRequest.includesPendingChanges = false
+        fetchRequest.resultType = .DictionaryResultType
+        
+        let entityDescription = fetchRequest.entity!
+        let propertiesByName = entityDescription.propertiesByName
+        let attributesByName = entityDescription.attributesByName
+        
+        var propertiesToFetch = [AnyObject]()
+        for term in self.selectTerms {
+            
+            switch term {
+                
+            case ._Attribute(let keyPath):
+                if let propertyDescription = propertiesByName[keyPath] as? NSPropertyDescription {
+                    
+                    propertiesToFetch.append(propertyDescription)
+                }
+                else {
+                    
+                    CoreStore.log(.Warning, message: "The property \"\(keyPath)\" does not exist in entity <\(entityDescription.managedObjectClassName)> and will be ignored by \(typeName(self)) query clause.")
+                }
+                
+            case ._Aggregate(let function, let keyPath, let alias):
+                if let attributeDescription = attributesByName[keyPath] as? NSAttributeDescription {
+                    
+                    let expressionDescription = NSExpressionDescription()
+                    expressionDescription.name = alias
+                    expressionDescription.expressionResultType = attributeDescription.attributeType
+                    expressionDescription.expression = NSExpression(
+                        forFunction: function,
+                        arguments: [NSExpression(forKeyPath: keyPath)]
+                    )
+                    
+                    propertiesToFetch.append(expressionDescription)
+                }
+                else {
+                    
+                    CoreStore.log(.Warning, message: "The attribute \"\(keyPath)\" does not exist in entity <\(entityDescription.managedObjectClassName)> and will be ignored by \(typeName(self)) query clause.")
+                }
+            }
+        }
+        
+        fetchRequest.propertiesToFetch = propertiesToFetch
+    }
+    
+    internal func keyPathForFirstSelectTerm() -> KeyPath {
+        
+        switch self.selectTerms.first! {
+            
+        case ._Attribute(let keyPath):
+            return keyPath
+            
+        case ._Aggregate(_, _, let alias):
+            return alias
+        }
+    }
+    
+    
+    // MARK: Private
+    
+    private let selectTerms: [SelectTerm]
+}
+
+
+// MARK: - Bool: SelectValueResultType
+
+extension Bool: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .BooleanAttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Bool? {
+        
+        return (result as? NSNumber)?.boolValue
+    }
+}
+
+
+// MARK: - Int8: SelectValueResultType
+
+extension Int8: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .Integer64AttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Int8? {
+        
+        if let value = (result as? NSNumber)?.longLongValue {
+            
+            return numericCast(value) as Int8
+        }
+        return nil
+    }
+}
+
+
+// MARK: - Int16: SelectValueResultType
+
+extension Int16: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .Integer64AttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Int16? {
+        
+        if let value = (result as? NSNumber)?.longLongValue {
+            
+            return numericCast(value) as Int16
+        }
+        return nil
+    }
+}
+
+
+// MARK: - Int32: SelectValueResultType
+
+extension Int32: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .Integer64AttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Int32? {
+        
+        if let value = (result as? NSNumber)?.longLongValue {
+            
+            return numericCast(value) as Int32
+        }
+        return nil
+    }
+}
+
+
+// MARK: - Int64: SelectValueResultType
+
+extension Int64: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .Integer64AttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Int64? {
+        
+        return (result as? NSNumber)?.longLongValue
+    }
+}
+
+
+// MARK: - Int: SelectValueResultType
+
+extension Int: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .Integer64AttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Int? {
+        
+        if let value = (result as? NSNumber)?.longLongValue {
+            
+            return numericCast(value) as Int
+        }
+        return nil
+    }
+}
+
+
+// MARK: - Double : SelectValueResultType
+
+extension Double: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .DoubleAttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Double? {
+        
+        return (result as? NSNumber)?.doubleValue
+    }
+}
+
+
+// MARK: - Float: SelectValueResultType
+
+extension Float: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .FloatAttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> Float? {
+        
+        return (result as? NSNumber)?.floatValue
+    }
+}
+
+
+// MARK: - String: SelectValueResultType
+
+extension String: SelectValueResultType {
+    
+    public static var attributeType: NSAttributeType {
+        
+        return .StringAttributeType
+    }
+    
+    public static func fromResultObject(result: AnyObject) -> String? {
+        
+        return result as? NSString as? String
+    }
+}
+
+
+// MARK: - NSNumber: SelectValueResultType
+
+extension NSNumber: SelectValueResultType {
+    
+    public class var attributeType: NSAttributeType {
+        
+        return .Integer64AttributeType
+    }
+    
+    public class func fromResultObject(result: AnyObject) -> Self? {
+        
+        func forceCast<T: NSNumber>(object: AnyObject) -> T? {
+            
+            return (object as? T)
+        }
+        return forceCast(result)
+    }
+}
+
+
+// MARK: - NSString: SelectValueResultType
+
+extension NSString: SelectValueResultType {
+    
+    public class var attributeType: NSAttributeType {
+        
+        return .StringAttributeType
+    }
+    
+    public class func fromResultObject(result: AnyObject) -> Self? {
+        
+        func forceCast<T: NSString>(object: AnyObject) -> T? {
+            
+            return (object as? T)
+        }
+        return forceCast(result)
+    }
+}
+
+
+// MARK: - NSDecimalNumber: SelectValueResultType
+
+extension NSDecimalNumber: SelectValueResultType {
+    
+    public override class var attributeType: NSAttributeType {
+        
+        return .DecimalAttributeType
+    }
+    
+    public override class func fromResultObject(result: AnyObject) -> Self? {
+        
+        func forceCast<T: NSDecimalNumber>(object: AnyObject) -> T? {
+            
+            return (object as? T)
+        }
+        return forceCast(result)
+    }
+}
+
+
+// MARK: - NSDate: SelectValueResultType
+
+extension NSDate: SelectValueResultType {
+    
+    public class var attributeType: NSAttributeType {
+        
+        return .DateAttributeType
+    }
+    
+    public class func fromResultObject(result: AnyObject) -> Self? {
+        
+        func forceCast<T: NSDate>(object: AnyObject) -> T? {
+            
+            return (object as? T)
+        }
+        return forceCast(result)
+    }
+}
+
+
+// MARK: - NSData: SelectValueResultType
+
+extension NSData: SelectValueResultType {
+    
+    public class var attributeType: NSAttributeType {
+        
+        return .BinaryDataAttributeType
+    }
+    
+    public class func fromResultObject(result: AnyObject) -> Self? {
+        
+        func forceCast<T: NSData>(object: AnyObject) -> T? {
+            
+            return (object as? T)
+        }
+        return forceCast(result)
+    }
+}
+
+
+// MARK: - NSManagedObjectID: SelectValueResultType
+
+extension NSManagedObjectID: SelectValueResultType {
+    
+    public class var attributeType: NSAttributeType {
+        
+        return .ObjectIDAttributeType
+    }
+    
+    public class func fromResultObject(result: AnyObject) -> Self? {
+        
+        func forceCast<T: NSManagedObjectID>(object: AnyObject) -> T? {
+            
+            return (object as? T)
+        }
+        return forceCast(result)
+    }
+}
+
+
+// MARK: - NSManagedObjectID: SelectAttributesResultType
+
+extension NSDictionary: SelectAttributesResultType {
+    
+    // MARK: SelectAttributesResultType
+    
+    public class func fromResultObjects(result: [AnyObject]) -> [[NSString: AnyObject]] {
+        
+        return result as! [[NSString: AnyObject]]
+    }
+}

CoreStore/Fetching and Querying/Concrete Clauses/Tweak.swift

@@ -0,0 +1,69 @@
+//
+//  Tweak.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - Tweak
+
+/**
+The `Tweak` clause allows fine-tuning the `NSFetchRequest` for a fetch or query.
+
+Sample usage:
+
+    let employees = transaction.fetchAll(
+        From(MyPersonEntity),
+        Tweak { (fetchRequest) -> Void in
+            fetchRequest.includesPendingChanges = false
+            fetchRequest.fetchLimit = 5
+        }
+    )
+*/
+public struct Tweak: FetchClause, QueryClause, DeleteClause {
+    
+    // MARK: Public
+    
+    /**
+    Initializes a `Tweak` clause with a closure where the `NSFetchRequest` may be configured.
+    
+    :param: customization a list of key path strings to group results with
+    */
+    public init(_ customization: (fetchRequest: NSFetchRequest) -> Void) {
+        
+        self.customization = customization
+    }
+    
+    
+    // MARK: FetchClause, QueryClause, DeleteClause
+    
+    public func applyToFetchRequest(fetchRequest: NSFetchRequest) {
+        
+        self.customization(fetchRequest: fetchRequest)
+    }
+    
+    
+    private let customization: (fetchRequest: NSFetchRequest) -> Void
+}

CoreStore/Fetching and Querying/Concrete Clauses/Where.swift

@@ -0,0 +1,131 @@
+//
+//  Where.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+public func &&(left: Where, right: Where) -> Where {
+    
+    return Where(NSCompoundPredicate(type: .AndPredicateType, subpredicates: [left.predicate, right.predicate]))
+}
+
+public func ||(left: Where, right: Where) -> Where {
+    
+    return Where(NSCompoundPredicate(type: .OrPredicateType, subpredicates: [left.predicate, right.predicate]))
+}
+
+public prefix func !(clause: Where) -> Where {
+    
+    return Where(NSCompoundPredicate(type: .NotPredicateType, subpredicates: [clause.predicate]))
+}
+
+
+// MARK: - Where
+
+/**
+The `Where` clause specifies the conditions for a fetch or a query.
+*/
+public struct Where: FetchClause, QueryClause, DeleteClause {
+    
+    // MARK: Public
+    
+    /**
+    Initializes a `Where` clause with an `NSPredicate`
+    
+    :param: predicate the `NSPredicate` for the fetch or query
+    */
+    public init(_ predicate: NSPredicate) {
+        
+        self.predicate = predicate
+    }
+    
+    /**
+    Initializes a `Where` clause with a predicate that always evaluates to `true`
+    */
+    public init() {
+        
+        self.init(true)
+    }
+    
+    /**
+    Initializes a `Where` clause with a predicate that always evaluates to the specified boolean value
+    
+    :param: value the boolean value for the predicate
+    */
+    public init(_ value: Bool) {
+        
+        self.init(NSPredicate(value: value))
+    }
+    
+    /**
+    Initializes a `Where` clause with a predicate using the specified string format and arguments
+    
+    :param: format the format string for the predicate
+    :param: args the arguments for `format`
+    */
+    public init(_ format: String, _ args: NSObject...) {
+        
+        self.init(NSPredicate(format: format, argumentArray: args))
+    }
+    
+    /**
+    Initializes a `Where` clause with a predicate using the specified string format and arguments
+    
+    :param: format the format string for the predicate
+    :param: argumentArray the arguments for `format`
+    */
+    public init(_ format: String, argumentArray: [NSObject]?) {
+        
+        self.init(NSPredicate(format: format, argumentArray: argumentArray))
+    }
+    
+    /**
+    Initializes a `Where` clause with a predicate using the specified string format and arguments
+    
+    :param: format the format string for the predicate
+    :param: argumentArray the arguments for `format`
+    */
+    public init(_ keyPath: KeyPath, isEqualTo value: NSObject?) {
+        
+        self.init(value == nil
+            ? NSPredicate(format: "\(keyPath) == nil")
+            : NSPredicate(format: "\(keyPath) == %@", value!))
+    }
+    
+    public let predicate: NSPredicate
+    
+    
+    // MARK: FetchClause, QueryClause, DeleteClause
+    
+    public func applyToFetchRequest(fetchRequest: NSFetchRequest) {
+        
+        if fetchRequest.predicate != nil {
+            
+            CoreStore.log(.Warning, message: "An existing predicate for the <\(NSFetchRequest.self)> was overwritten by \(typeName(self)) query clause.")
+        }
+        
+        fetchRequest.predicate = self.predicate
+    }
+}

CoreStore/Fetching and Querying/CoreStore+Querying.swift

@@ -0,0 +1,213 @@
+//
+//  CoreStore+Querying.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+// MARK: - CoreStore
+
+public extension CoreStore {
+    
+    // MARK: Public
+    
+    /**
+    Using the `defaultStack`, fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the first `NSManagedObject` instance that satisfies the specified `FetchClause`s
+    */
+    public static func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
+        
+        return self.defaultStack.fetchOne(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the first `NSManagedObject` instance that satisfies the specified `FetchClause`s
+    */
+    public static func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
+        
+        return self.defaultStack.fetchOne(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches all `NSManagedObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: all `NSManagedObject` instances that satisfy the specified `FetchClause`s
+    */
+    public static func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
+        
+        return self.defaultStack.fetchAll(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches all `NSManagedObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: all `NSManagedObject` instances that satisfy the specified `FetchClause`s
+    */
+    public static func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
+        
+        return self.defaultStack.fetchAll(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the number of `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public static func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
+        
+        return self.defaultStack.fetchCount(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the number of `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public static func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
+        
+        return self.defaultStack.fetchCount(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s
+    */
+    public static func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
+        
+        return self.defaultStack.fetchObjectID(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s
+    */
+    public static func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
+        
+        return self.defaultStack.fetchObjectID(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public static func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
+        
+        return self.defaultStack.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public static func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
+        
+        return self.defaultStack.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, queries aggregate values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public static func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
+        
+        return self.defaultStack.queryValue(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, queries aggregate values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public static func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
+        
+        return self.defaultStack.queryValue(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, queries a dictionary of attribtue values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public static func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
+        
+        return self.defaultStack.queryAttributes(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, queries a dictionary of attribute values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public static func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: [QueryClause]) -> [[NSString: AnyObject]]? {
+        
+        return self.defaultStack.queryAttributes(from, selectClause, queryClauses)
+    }
+}

CoreStore/Fetching and Querying/DataStack+Querying.swift

@@ -0,0 +1,244 @@
+//
+//  DataStack+Querying.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - DataStack
+
+public extension DataStack {
+    
+    // MARK: Public
+    
+    /**
+    Fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the first `NSManagedObject` instance that satisfies the specified `FetchClause`s
+    */
+    public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchOne(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the first `NSManagedObject` instance that satisfies the specified `FetchClause`s
+    */
+    public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchOne(from, fetchClauses)
+    }
+    
+    /**
+    Fetches all `NSManagedObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: all `NSManagedObject` instances that satisfy the specified `FetchClause`s
+    */
+    public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchAll(from, fetchClauses)
+    }
+    
+    /**
+    Fetches all `NSManagedObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: all `NSManagedObject` instances that satisfy the specified `FetchClause`s
+    */
+    public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchAll(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the number of `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchCount(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the number of `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the number `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchCount(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s
+    */
+    public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchObjectID(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for the first `NSManagedObject` that satisfies the specified `FetchClause`s
+    */
+    public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchObjectID(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    /**
+    Fetches the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: the `NSManagedObjectID` for all `NSManagedObject`'s that satisfy the specified `FetchClause`s
+    */
+    public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to fetch from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    /**
+    Queries aggregate values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to query from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.queryValue(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Queries aggregate values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to query from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.queryValue(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Queries a dictionary of attribute values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to query from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.queryAttributes(from, selectClause, queryClauses)
+    }
+    
+    /**
+    Queries a dictionary of attribute values as specified by the `QueryClause`'s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    
+    A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: selectClause a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
+    :param: queryClauses a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
+    :returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
+    */
+    public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: [QueryClause]) -> [[NSString: AnyObject]]? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to query from a \(typeName(self)) outside the main thread.")
+        
+        return self.mainContext.queryAttributes(from, selectClause, queryClauses)
+    }
+}

CoreStore/Fetching and Querying/Protocol Clauses/ClauseTypes.swift

@@ -0,0 +1,51 @@
+//
+//  ClauseTypes.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - FetchClause
+
+public protocol FetchClause {
+    
+    func applyToFetchRequest(fetchRequest: NSFetchRequest)
+}
+
+
+// MARK: - QueryClause
+
+public protocol QueryClause {
+    
+    func applyToFetchRequest(fetchRequest: NSFetchRequest)
+}
+
+
+// MARK: - DeleteClause
+
+public protocol DeleteClause {
+    
+    func applyToFetchRequest(fetchRequest: NSFetchRequest)
+}

CoreStore/Info.plist

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>com.johnestropia.$(PRODUCT_NAME:rfc1034identifier)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>FMWK</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>$(CURRENT_PROJECT_VERSION)</string>
+	<key>NSPrincipalClass</key>
+	<string></string>
+</dict>
+</plist>

CoreStore/Internal/AssociatedObjects.swift

@@ -0,0 +1,68 @@
+//
+//  NSObject+CoreStore.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+internal func getAssociatedObjectForKey<T: AnyObject>(key: UnsafePointer<Void>, inObject object: AnyObject) -> T? {
+    
+    switch objc_getAssociatedObject(object, key) {
+        
+    case let associatedObject as T:
+        return associatedObject
+        
+    case let associatedObject as WeakObject:
+        return associatedObject.object as? T
+        
+    default:
+        return nil
+    }
+}
+
+internal func setAssociatedRetainedObject<T: AnyObject>(associatedObject: T?, forKey key: UnsafePointer<Void>, inObject object: AnyObject) {
+    
+    objc_setAssociatedObject(object, key, associatedObject, UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
+}
+
+internal func setAssociatedCopiedObject<T: AnyObject>(associatedObject: T?, forKey key: UnsafePointer<Void>, inObject object: AnyObject) {
+    
+    objc_setAssociatedObject(object, key, associatedObject, UInt(OBJC_ASSOCIATION_COPY_NONATOMIC))
+}
+
+internal func setAssociatedAssignedObject<T: AnyObject>(associatedObject: T?, forKey key: UnsafePointer<Void>, inObject object: AnyObject) {
+    
+    objc_setAssociatedObject(object, key, associatedObject, UInt(OBJC_ASSOCIATION_ASSIGN))
+}
+
+internal func setAssociatedWeakObject<T: AnyObject>(associatedObject: T?, forKey key: UnsafePointer<Void>, inObject object: AnyObject) {
+    
+    if let associatedObject = associatedObject {
+        
+        objc_setAssociatedObject(object, key, WeakObject(associatedObject), UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
+    }
+    else {
+        
+        objc_setAssociatedObject(object, key, nil, UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
+    }
+}

CoreStore/Internal/NSManagedObject+Transaction.swift

@@ -0,0 +1,91 @@
+//
+//  NSManagedObject+Transaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - NSManagedObject
+
+internal extension NSManagedObject {
+    
+    // MARK: Internal
+    
+    internal class func createInContext(context: NSManagedObjectContext) -> Self {
+        
+        return self(
+            entity: context.entityDescriptionForEntityClass(self)!,
+            insertIntoManagedObjectContext: context
+        )
+    }
+    
+    internal func inContext(context: NSManagedObjectContext) -> Self? {
+        
+        return self.typedObjectInContext(context)
+    }
+    
+    internal func deleteFromContext() {
+        
+        self.managedObjectContext?.deleteObject(self)
+    }
+    
+    
+    // MARK: Private
+    
+    private func typedObjectInContext<T: NSManagedObject>(context: NSManagedObjectContext) -> T? {
+        
+        let objectID = self.objectID
+        if objectID.temporaryID {
+            
+            var error: NSError?
+            var didSucceed: Bool?
+            if let managedObjectContext = self.managedObjectContext {
+                
+                managedObjectContext.performBlockAndWait {
+                    
+                    didSucceed = managedObjectContext.obtainPermanentIDsForObjects([self], error: &error)
+                }
+            }
+            if didSucceed != true {
+                
+                CoreStore.handleError(
+                    error ?? NSError(coreStoreErrorCode: .UnknownError),
+                    "Failed to obtain permanent ID for object.")
+                return nil
+            }
+        }
+        
+        var error: NSError?
+        if let existingObject = context.existingObjectWithID(objectID, error: &error) {
+            
+            return (existingObject as! T)
+        }
+        
+        CoreStore.handleError(
+            error ?? NSError(coreStoreErrorCode: .UnknownError),
+            "Failed to load existing <\(T.self)> in context.")
+        return nil;
+    }
+}

CoreStore/Internal/NSManagedObjectContext+CoreStore.swift

@@ -0,0 +1,131 @@
+//
+//  NSManagedObjectContext+CoreStore.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - NSManagedObjectContext
+
+internal extension NSManagedObjectContext {
+    
+    // MARK: Internal
+    
+    internal var shouldCascadeSavesToParent: Bool {
+        
+        get {
+            
+            let number: NSNumber? = getAssociatedObjectForKey(
+                &PropertyKeys.shouldCascadeSavesToParent,
+                inObject: self
+            )
+            return number?.boolValue ?? false
+        }
+        set {
+            
+            setAssociatedCopiedObject(
+                NSNumber(bool: newValue),
+                forKey: &PropertyKeys.shouldCascadeSavesToParent,
+                inObject: self
+            )
+        }
+    }
+    
+    internal func entityDescriptionForEntityClass(entity: NSManagedObject.Type) -> NSEntityDescription? {
+        
+        if let entityName = self.parentStack?.entityNameForEntityClass(entity) {
+
+            return NSEntityDescription.entityForName(
+                entityName,
+                inManagedObjectContext: self
+            )
+        }
+        return nil
+    }
+    
+    internal func setupForCoreStoreWithContextName(contextName: String) {
+        
+        if self.respondsToSelector("setName:") {
+            
+            self.name = contextName
+        }
+        
+        self.observerForWillSaveNotification = NotificationObserver(
+            notificationName: NSManagedObjectContextWillSaveNotification,
+            object: self,
+            closure: { (note) -> Void in
+                
+                let context = note.object as! NSManagedObjectContext
+                let insertedObjects = context.insertedObjects
+                let numberOfInsertedObjects = insertedObjects.count
+                if numberOfInsertedObjects <= 0 {
+                    
+                    return
+                }
+                
+                var error: NSError?
+                if context.obtainPermanentIDsForObjects(Array(insertedObjects), error: &error) {
+                    
+                    return
+                }
+                
+                CoreStore.handleError(
+                    error ?? NSError(coreStoreErrorCode: .UnknownError),
+                    "Failed to obtain permanent ID(s) for \(numberOfInsertedObjects) inserted object(s)."
+                )
+            }
+        )
+    }
+    
+    
+    // MARK: Private
+    
+    private struct PropertyKeys {
+        
+        static var observerForWillSaveNotification: Void?
+        static var shouldCascadeSavesToParent: Void?
+    }
+    
+    private var observerForWillSaveNotification: NotificationObserver? {
+        
+        get {
+            
+            return getAssociatedObjectForKey(
+                &PropertyKeys.observerForWillSaveNotification,
+                inObject: self
+            )
+        }
+        set {
+            
+            setAssociatedRetainedObject(
+                newValue,
+                forKey: &PropertyKeys.observerForWillSaveNotification,
+                inObject: self
+            )
+        }
+    }
+}
+

CoreStore/Internal/NSManagedObjectContext+Querying.swift

@@ -0,0 +1,330 @@
+//
+//  NSManagedObjectContext+Querying.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - NSManagedObjectContext
+
+internal extension NSManagedObjectContext {
+    
+    // MARK: Public
+    
+    internal func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
+        
+        return self.fetchOne(from, fetchClauses)
+    }
+    
+    internal func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 1
+        fetchRequest.resultType = .ManagedObjectResultType
+        
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var fetchResults: [T]?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            fetchResults = self.executeFetchRequest(fetchRequest, error: &error) as? [T]
+        }
+        if fetchResults == nil {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed executing fetch request.")
+            return nil
+        }
+        
+        return fetchResults?.first
+    }
+    
+    internal func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
+        
+        return self.fetchAll(from, fetchClauses)
+    }
+    
+    internal func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 0
+        fetchRequest.resultType = .ManagedObjectResultType
+        
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var fetchResults: [T]?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            fetchResults = self.executeFetchRequest(fetchRequest, error: &error) as? [T]
+        }
+        if fetchResults == nil {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed executing fetch request.")
+            return nil
+        }
+        
+        return fetchResults
+    }
+    
+    internal func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
+    
+        return self.fetchCount(from, fetchClauses)
+    }
+    
+    internal func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var count = 0
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            count = self.countForFetchRequest(fetchRequest, error: &error)
+        }
+        if count == NSNotFound {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed executing fetch request.")
+            return nil
+        }
+        
+        return count
+    }
+    
+    internal func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
+        
+        return self.fetchObjectID(from, fetchClauses)
+    }
+    
+    internal func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 1
+        fetchRequest.resultType = .ManagedObjectIDResultType
+        
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var fetchResults: [NSManagedObjectID]?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            fetchResults = self.executeFetchRequest(fetchRequest, error: &error) as? [NSManagedObjectID]
+        }
+        if fetchResults == nil {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed executing fetch request.")
+            return nil
+        }
+        
+        return fetchResults?.first
+    }
+    
+    internal func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
+        
+        return self.fetchObjectIDs(from, fetchClauses)
+    }
+    
+    internal func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 0
+        fetchRequest.resultType = .ManagedObjectIDResultType
+        
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var fetchResults: [NSManagedObjectID]?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            fetchResults = self.executeFetchRequest(fetchRequest, error: &error) as? [NSManagedObjectID]
+        }
+        if fetchResults == nil {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed executing fetch request.")
+            return nil
+        }
+        
+        return fetchResults
+    }
+    
+    internal func deleteAll<T: NSManagedObject>(from: From<T>, _ deleteClauses: DeleteClause...) -> Int? {
+        
+        return self.deleteAll(from, deleteClauses)
+    }
+    
+    internal func deleteAll<T: NSManagedObject>(from: From<T>, _ deleteClauses: [DeleteClause]) -> Int? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 0
+        fetchRequest.resultType = .ManagedObjectResultType
+        fetchRequest.returnsObjectsAsFaults = true
+        
+        for clause in deleteClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var numberOfDeletedObjects: Int?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            autoreleasepool {
+                
+                if let fetchResults = self.executeFetchRequest(fetchRequest, error: &error) as? [T] {
+                    
+                    numberOfDeletedObjects = fetchResults.count
+                    for object in fetchResults {
+                        
+                        self.deleteObject(object)
+                    }
+                }
+            }
+        }
+        if numberOfDeletedObjects == nil {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed executing fetch request.")
+            return nil
+        }
+        
+        return numberOfDeletedObjects
+    }
+    
+    internal func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
+        
+        return self.queryValue(from, selectClause, queryClauses)
+    }
+    
+    internal func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 0
+        
+        selectClause.applyToFetchRequest(fetchRequest)
+        
+        for clause in queryClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var fetchResults: [AnyObject]?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            fetchResults = self.executeFetchRequest(fetchRequest, error: &error)
+        }
+        if let fetchResults = fetchResults {
+            
+            if let rawResult = fetchResults.first as? NSDictionary,
+                let rawObject: AnyObject = rawResult[selectClause.keyPathForFirstSelectTerm()] {
+                    
+                    return Select<U>.ReturnType.fromResultObject(rawObject)
+            }
+            return nil
+        }
+        
+        CoreStore.handleError(
+            error ?? NSError(coreStoreErrorCode: .UnknownError),
+            "Failed executing fetch request.")
+        return nil
+    }
+    
+    internal func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
+        
+        return self.queryAttributes(from, selectClause, queryClauses)
+    }
+    
+    internal func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: [QueryClause]) -> [[NSString: AnyObject]]? {
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: self)
+        
+        fetchRequest.fetchLimit = 0
+        
+        selectClause.applyToFetchRequest(fetchRequest)
+        
+        for clause in queryClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        var fetchResults: [AnyObject]?
+        var error: NSError?
+        self.performBlockAndWait {
+            
+            fetchResults = self.executeFetchRequest(fetchRequest, error: &error)
+        }
+        if let fetchResults = fetchResults {
+            
+            return Select<NSDictionary>.ReturnType.fromResultObjects(fetchResults)
+        }
+        
+        CoreStore.handleError(
+            error ?? NSError(coreStoreErrorCode: .UnknownError),
+            "Failed executing fetch request.")
+        return nil
+    }
+}

CoreStore/Internal/NSManagedObjectContext+Setup.swift

@@ -0,0 +1,123 @@
+//
+//  NSManagedObjectContext+Setup.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - NSManagedObjectContext
+
+internal extension NSManagedObjectContext {
+    
+    // MARK: Internal
+    
+    internal weak var parentStack: DataStack? {
+        
+        get {
+            
+            if let parentContext = self.parentContext {
+                
+                return parentContext.parentStack
+            }
+            
+            return getAssociatedObjectForKey(&PropertyKeys.parentStack, inObject: self)
+        }
+        set {
+            
+            if self.parentContext != nil {
+                
+                return
+            }
+            
+            setAssociatedWeakObject(
+                newValue,
+                forKey: &PropertyKeys.parentStack,
+                inObject: self
+            )
+        }
+    }
+    
+    internal class func rootSavingContextForCoordinator(coordinator: NSPersistentStoreCoordinator) -> NSManagedObjectContext {
+        
+        let context = NSManagedObjectContext(concurrencyType: .PrivateQueueConcurrencyType)
+        context.persistentStoreCoordinator = coordinator
+        context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
+        context.undoManager = nil
+        context.setupForCoreStoreWithContextName("com.corestore.rootcontext")
+        
+        return context
+    }
+    
+    internal class func mainContextForRootContext(rootContext: NSManagedObjectContext) -> NSManagedObjectContext {
+        
+        let context = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
+        context.parentContext = rootContext
+        context.shouldCascadeSavesToParent = true
+        context.undoManager = nil
+        context.setupForCoreStoreWithContextName("com.corestore.maincontext")
+        context.observerForDidSaveNotification = NotificationObserver(
+            notificationName: NSManagedObjectContextDidSaveNotification,
+            object: rootContext,
+            closure: { [weak context] (note) -> Void in
+                
+                context?.performBlockAndWait { () -> Void in
+                    
+                    context?.mergeChangesFromContextDidSaveNotification(note)
+                }
+                return
+            }
+        )
+        
+        return context
+    }
+    
+    
+    // MARK: Private
+    
+    private struct PropertyKeys {
+        
+        static var parentStack: Void?
+        static var observerForDidSaveNotification: Void?
+    }
+    
+    private var observerForDidSaveNotification: NotificationObserver? {
+        
+        get {
+            
+            return getAssociatedObjectForKey(
+                &PropertyKeys.observerForDidSaveNotification,
+                inObject: self
+            )
+        }
+        set {
+            
+            setAssociatedRetainedObject(
+                newValue,
+                forKey: &PropertyKeys.observerForDidSaveNotification,
+                inObject: self
+            )
+        }
+    }
+}

CoreStore/Internal/NSManagedObjectContext+Transaction.swift

@@ -0,0 +1,188 @@
+//
+//  NSManagedObjectContext+Transaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - NSManagedObjectContext
+
+internal extension NSManagedObjectContext {
+    
+    // MARK: Internal
+    
+    internal weak var parentTransaction: BaseDataTransaction? {
+        
+        get {
+            
+            return getAssociatedObjectForKey(
+                &PropertyKeys.parentTransaction,
+                inObject: self
+            )
+        }
+        set {
+            
+            setAssociatedWeakObject(
+                newValue,
+                forKey: &PropertyKeys.parentTransaction,
+                inObject: self
+            )
+        }
+    }
+    
+    internal func temporaryContextInTransactionWithConcurrencyType(concurrencyType: NSManagedObjectContextConcurrencyType) -> NSManagedObjectContext {
+        
+        let context = NSManagedObjectContext(concurrencyType: concurrencyType)
+        context.parentContext = self
+        context.parentStack = self.parentStack
+        context.setupForCoreStoreWithContextName("com.corestore.temporarycontext")
+        context.shouldCascadeSavesToParent = (self.parentStack?.rootSavingContext == self)
+        context.retainsRegisteredObjects = true
+        
+        return context
+    }
+    
+    internal func saveSynchronously() -> SaveResult {
+        
+        var result = SaveResult(hasChanges: false)
+        self.performBlockAndWait {
+            [unowned self] () -> Void in
+            
+            if !self.hasChanges {
+                
+                return
+            }
+            
+            var saveError: NSError?
+            if self.save(&saveError) {
+                
+                if self.shouldCascadeSavesToParent {
+                    
+                    if let parentContext = self.parentContext {
+                        
+                        switch parentContext.saveSynchronously() {
+                            
+                        case .Success(let hasChanges):
+                            result = SaveResult(hasChanges: true)
+                        case .Failure(let error):
+                            result = SaveResult(error)
+                        }
+                        return
+                    }
+                }
+                
+                result = SaveResult(hasChanges: true)
+            }
+            else if let error = saveError {
+                
+                CoreStore.handleError(
+                    error,
+                    "Failed to save <\(NSManagedObjectContext.self)>.")
+                result = SaveResult(error)
+            }
+            else {
+                
+                result = SaveResult(hasChanges: false)
+            }
+        }
+        
+        return result
+    }
+    
+    internal func saveAsynchronouslyWithCompletion(completion: ((result: SaveResult) -> Void)?) {
+        
+        self.performBlock { () -> Void in
+            
+            if !self.hasChanges {
+                
+                if let completion = completion {
+                    
+                    GCDQueue.Main.async {
+                        
+                        completion(result: SaveResult(hasChanges: false))
+                    }
+                }
+                return
+            }
+            
+            var saveError: NSError?
+            if self.save(&saveError) {
+                
+                if self.shouldCascadeSavesToParent {
+                    
+                    if let parentContext = self.parentContext {
+                        
+                        let result = parentContext.saveSynchronously()
+                        if let completion = completion {
+                            
+                            GCDQueue.Main.async {
+                                
+                                completion(result: result)
+                            }
+                        }
+                        return
+                    }
+                }
+                
+                if let completion = completion {
+                    
+                    GCDQueue.Main.async {
+                        
+                        completion(result: SaveResult(hasChanges: true))
+                    }
+                }
+            }
+            else if let error = saveError {
+                
+                CoreStore.handleError(
+                    error,
+                    "Failed to save <\(NSManagedObjectContext.self)>.")
+                if let completion = completion {
+                    
+                    GCDQueue.Main.async {
+                        
+                        completion(result: SaveResult(error))
+                    }
+                }
+            }
+            else if let completion = completion {
+                
+                GCDQueue.Main.async {
+                    
+                    completion(result: SaveResult(hasChanges: false))
+                }
+            }
+        }
+    }
+    
+    
+    // MARK: Private
+    
+    private struct PropertyKeys {
+        
+        static var parentTransaction: Void?
+    }
+}

CoreStore/Internal/NotificationObserver.swift

@@ -0,0 +1,59 @@
+//
+//  NotificationObserver.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - NotificationObserver
+
+internal final class NotificationObserver {
+    
+    // MARK: Public
+    
+    let notificationName: String
+    let object: AnyObject?
+    let observer: NSObjectProtocol
+    
+    init(notificationName: String, object: AnyObject?, closure: (note: NSNotification!) -> Void) {
+        
+        self.notificationName = notificationName
+        self.object = object
+        self.observer = NSNotificationCenter.defaultCenter().addObserverForName(
+            notificationName,
+            object: object,
+            queue: nil,
+            usingBlock: closure
+        )
+    }
+    
+    deinit {
+        
+        NSNotificationCenter.defaultCenter().removeObserver(
+            self.observer,
+            name: self.notificationName,
+            object: self.object
+        )
+    }
+}

CoreStore/Internal/WeakObject.swift

@@ -0,0 +1,44 @@
+//
+//  WeakObject.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - WeakObject
+
+internal final class WeakObject {
+    
+    // MARK: Internal
+    
+    internal init(_ object: AnyObject) {
+        
+        self.object = object
+    }
+    
+    
+    // MARK: Private
+    
+    private(set) weak var object: AnyObject?
+}

CoreStore/Logging/CoreStore+Logging.swift

@@ -0,0 +1,75 @@
+//
+//  CoreStore+Logging.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - CoreStore
+
+public extension CoreStore {
+    
+    // MARK: Public
+    
+    /**
+    The `CoreStoreLogger` instance to be used. The default logger is an instance of a `DefaultLogger`.
+    */
+    public static var logger: CoreStoreLogger = DefaultLogger()
+    
+    
+    // MARK: Internal
+    
+    internal static func log(level: LogLevel, message: String, fileName: StaticString = __FILE__, lineNumber: Int = __LINE__, functionName: StaticString = __FUNCTION__) {
+        
+        self.logger.log(
+            level: level,
+            message: message,
+            fileName: fileName,
+            lineNumber:
+            lineNumber,
+            functionName:
+            functionName
+        )
+    }
+    
+    internal static func handleError(error: NSError, _ message: String, fileName: StaticString = __FILE__, lineNumber: Int = __LINE__, functionName: StaticString = __FUNCTION__) {
+        
+        self.logger.handleError(
+            error: error,
+            message: message,
+            fileName: fileName,
+            lineNumber: lineNumber,
+            functionName: functionName)
+    }
+    
+    internal static func assert(@autoclosure condition: () -> Bool, _ message: String, fileName: StaticString = __FILE__, lineNumber: Int = __LINE__, functionName: StaticString = __FUNCTION__) {
+        
+        self.logger.assert(
+            condition,
+            message: message,
+            fileName: fileName,
+            lineNumber: lineNumber,
+            functionName: functionName)
+    }
+}

CoreStore/Logging/CoreStoreLogger.swift

@@ -0,0 +1,90 @@
+//
+//  CoreStoreLogger.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - LogLevel
+
+/**
+The `LogLevel` indicates the severity of a log message.
+*/
+public enum LogLevel {
+    
+    case Trace
+    case Notice
+    case Warning
+    case Fatal
+}
+
+
+// MARK: - CoreStoreLogger
+
+/**
+Custom loggers should implement the `CoreStoreLogger` protocol and pass its instance to `CoreStore.logger`. Calls to `log(...)`, `handleError(...)`, and `assert(...)` are not tied to a specific queue/thread, so it is the implementer's job to handle thread-safety.
+*/
+public protocol CoreStoreLogger {
+    
+    /**
+    Handles log messages sent by the `CoreStore` framework.
+    
+    :level: the severity of the log message
+    :message: the log message
+    :fileName: the source file name
+    :lineNumber: the source line number
+    :functionName: the source function name
+    */
+    func log(#level: LogLevel, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString)
+    
+    /**
+    Handles errors sent by the `CoreStore` framework.
+    
+    :error: the error
+    :message: the error message
+    :fileName: the source file name
+    :lineNumber: the source line number
+    :functionName: the source function name
+    */
+    func handleError(#error: NSError, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString)
+    
+    /**
+    Handles assertions made throughout the `CoreStore` framework.
+    
+    :condition: the assertion condition
+    :message: the assertion message
+    :fileName: the source file name
+    :lineNumber: the source line number
+    :functionName: the source function name
+    */
+    func assert(@autoclosure condition: () -> Bool, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString)
+}
+
+
+// MARK: - Utilities
+
+internal func typeName<T>(value: T) -> String {
+    
+    return "<\(_stdlib_getDemangledTypeName(value))>"
+}

CoreStore/Logging/DefaultLogger.swift

@@ -0,0 +1,67 @@
+//
+//  DefaultLogger.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - DefaultLogger
+
+/**
+The `DefaultLogger` is a basic implementation of the `CoreStoreLogger` protocol.
+
+- The `log(...)` method calls `println(...)` to print the level, source file name, line number, function name, and the log message.
+- The `handleError(...)` method calls `println(...)` to print the source file name, line number, function name, and the error message.
+- The `assert(...)` method calls `assert(...)` on the arguments.
+*/
+public final class DefaultLogger: CoreStoreLogger {
+   
+    public func log(#level: LogLevel, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString) {
+        
+        #if DEBUG
+            let levelString: String
+            switch level {
+            case .Trace: levelString = "Trace"
+            case .Notice: levelString = "Notice"
+            case .Warning: levelString = "Warning"
+            case .Fatal: levelString = "Fatal"
+            }
+            Swift.println("[CoreStore:\(levelString)] \(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message)\n")
+        #endif
+    }
+    
+    public func handleError(#error: NSError, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString) {
+        
+        #if DEBUG
+            Swift.println("[CoreStore:Error] \(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message): \(error)\n")
+        #endif
+    }
+    
+    public func assert(@autoclosure condition: () -> Bool, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString) {
+        
+        #if DEBUG
+            Swift.assert(condition, message, file: fileName, line: numericCast(lineNumber))
+        #endif
+    }
+}

CoreStore/NSError+CoreStore.swift

@@ -0,0 +1,79 @@
+//
+//  NSError+CoreStore.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+/**
+The `NSError` error domain for `CoreStore`.
+*/
+public let CoreStoreErrorDomain = "com.corestore.error"
+
+/**
+The `NSError` error codes for `CoreStoreErrorDomain`.
+*/
+public enum CoreStoreErrorCode: Int {
+    
+    /**
+    A failure occured because of an unknown error.
+    */
+    case UnknownError
+    
+    /**
+    The `NSPersistentStore` could note be initialized because another store existed at the specified `NSURL`.
+    */
+    case DifferentPersistentStoreExistsAtURL
+}
+
+
+// MARK: - NSError+CoreStore
+
+public extension NSError {
+   
+    /**
+    If the error's domain is equal to `CoreStoreErrorDomain`, returns the associated `CoreStoreErrorCode`. For other domains, returns `nil`.
+    */
+    public var coreStoreErrorCode: CoreStoreErrorCode? {
+        
+        return (self.domain == CoreStoreErrorDomain
+            ? CoreStoreErrorCode(rawValue: self.code)
+            : nil)
+    }
+    
+    
+    // MARK: Internal
+    
+    internal convenience init(coreStoreErrorCode: CoreStoreErrorCode) {
+        
+        self.init(coreStoreErrorCode: coreStoreErrorCode, userInfo: nil)
+    }
+    
+    internal convenience init(coreStoreErrorCode: CoreStoreErrorCode, userInfo: [NSObject: AnyObject]?) {
+        
+        self.init(
+            domain: CoreStoreErrorDomain,
+            code: coreStoreErrorCode.rawValue,
+            userInfo: userInfo)
+    }
+}

CoreStore/Observing/CoreStore+Observing.swift

@@ -0,0 +1,96 @@
+//
+//  CoreStore+Observing.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - CoreStore
+
+public extension CoreStore {
+    
+    // MARK: Public
+    
+    /**
+    Using the `defaultStack`, creates a `ManagedObjectController` for the specified `NSManagedObject`. Multiple `ManagedObjectObserver`'s may then register themselves to be notified when changes are made to the `NSManagedObject`.
+    
+    :param: object the `NSManagedObject` to observe changes from
+    :returns: a `ManagedObjectController` that monitors changes to `object`
+    */
+    public static func observeObject<T: NSManagedObject>(object: T) -> ManagedObjectController<T> {
+        
+        return self.defaultStack.observeObject(object)
+    }
+    
+    /**
+    Using the `defaultStack`, creates a `ManagedObjectListController` for a list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public static func observeObjectList<T: NSManagedObject>(from: From<T>, _ groupBy: GroupBy? = nil, _ queryClauses: FetchClause...) -> ManagedObjectListController<T> {
+        
+        return self.defaultStack.observeObjectList(from, queryClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, creates a `ManagedObjectListController` for a list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public static func observeObjectList<T: NSManagedObject>(from: From<T>, _ groupBy: GroupBy? = nil, _ queryClauses: [FetchClause]) -> ManagedObjectListController<T> {
+        
+        return self.defaultStack.observeObjectList(from, queryClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, creates a `ManagedObjectListController` for a sectioned list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: sectionedBy a `SectionedBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public static func observeSectionedList<T: NSManagedObject>(from: From<T>, _ sectionedBy: SectionedBy, _ fetchClauses: FetchClause...) -> ManagedObjectListController<T> {
+        
+        return self.defaultStack.observeSectionedList(from, sectionedBy, fetchClauses)
+    }
+    
+    /**
+    Using the `defaultStack`, creates a `ManagedObjectListController` for a sectioned list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: sectionedBy a `SectionedBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public static func observeSectionedList<T: NSManagedObject>(from: From<T>, _ sectionedBy: SectionedBy, _ fetchClauses: [FetchClause]) -> ManagedObjectListController<T> {
+        
+        return self.defaultStack.observeSectionedList(from, sectionedBy, fetchClauses)
+    }
+}

CoreStore/Observing/DataStack+Observing.swift

@@ -0,0 +1,116 @@
+//
+//  DataStack+Observing.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - DataStack
+
+public extension DataStack {
+    
+    // MARK: Public
+    
+    /**
+    Creates a `ManagedObjectController` for the specified `NSManagedObject`. Multiple `ManagedObjectObserver`'s may then register themselves to be notified when changes are made to the `NSManagedObject`.
+    
+    :param: object the `NSManagedObject` to observe changes from
+    :returns: a `ManagedObjectController` that monitors changes to `object`
+    */
+    public func observeObject<T: NSManagedObject>(object: T) -> ManagedObjectController<T> {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to observe objects from \(typeName(self)) outside the main thread.")
+        
+        return ManagedObjectController(
+            dataStack: self,
+            object: object
+        )
+    }
+    
+    /**
+    Creates a `ManagedObjectListController` for a list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public func observeObjectList<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> ManagedObjectListController<T> {
+        
+        return self.observeObjectList(from, fetchClauses)
+    }
+    
+    /**
+    Creates a `ManagedObjectListController` for a list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public func observeObjectList<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> ManagedObjectListController<T> {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to observe objects from \(typeName(self)) outside the main thread.")
+        
+        return ManagedObjectListController(
+            dataStack: self,
+            from: from,
+            sectionedBy: nil,
+            fetchClauses: fetchClauses
+        )
+    }
+    
+    /**
+    Creates a `ManagedObjectListController` for a sectioned list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: sectionedBy a `SectionedBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public func observeSectionedList<T: NSManagedObject>(from: From<T>, _ sectionedBy: SectionedBy, _ fetchClauses: FetchClause...) -> ManagedObjectListController<T> {
+     
+        return self.observeSectionedList(from, sectionedBy, fetchClauses)
+    }
+    
+    /**
+    Creates a `ManagedObjectListController` for a sectioned list of `NSManagedObject`'s that satisfy the specified fetch clauses. Multiple `ManagedObjectListObserver`'s may then register themselves to be notified when changes are made to the list.
+    
+    :param: from a `From` clause indicating the entity type
+    :param: sectionedBy a `SectionedBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+    :param: fetchClauses a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+    :returns: a `ManagedObjectListController` instance that monitors changes to the list
+    */
+    public func observeSectionedList<T: NSManagedObject>(from: From<T>, _ sectionedBy: SectionedBy, _ fetchClauses: [FetchClause]) -> ManagedObjectListController<T> {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to observe objects from \(typeName(self)) outside the main thread.")
+        
+        return ManagedObjectListController(
+            dataStack: self,
+            from: from,
+            sectionedBy: sectionedBy,
+            fetchClauses: fetchClauses
+        )
+    }
+}

CoreStore/Observing/ManagedObjectController.swift

@@ -0,0 +1,346 @@
+//
+//  ManagedObjectController.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+private let ManagedObjectListControllerWillChangeObjectNotification = "ManagedObjectListControllerWillChangeObjectNotification"
+private let ManagedObjectListControllerDidDeleteObjectNotification = "ManagedObjectListControllerDidDeleteObjectNotification"
+private let ManagedObjectListControllerDidUpdateObjectNotification = "ManagedObjectListControllerDidUpdateObjectNotification"
+
+private let UserInfoKeyObject = "UserInfoKeyObject"
+
+private struct NotificationKey {
+    
+    static var willChangeObject: Void?
+    static var didDeleteObject: Void?
+    static var didUpdateObject: Void?
+}
+
+
+// MARK: - ManagedObjectController
+
+/**
+The `ManagedObjectController` monitors changes to a single `NSManagedObject` instance. Observers that implement the `ManagedObjectObserver` protocol may then register themselves to the `ManagedObjectController`'s `addObserver(_:)` method:
+
+    let objectController = CoreStore.observeObject(object)
+    objectController.addObserver(self)
+
+The created `ManagedObjectController` instance needs to be held on (retained) for as long as the object needs to be observed.
+
+Observers registered via `addObserver(_:)` are not retained. `ManagedObjectController` only keeps a `weak` reference to all observers, thus keeping itself free from retain-cycles.
+*/
+public final class ManagedObjectController<T: NSManagedObject> {
+    
+    // MARK: Public
+    
+    /**
+    Returns the `NSManagedObject` instance being observed, or `nil` if the object was already deleted.
+    */
+    public var object: T? {
+        
+        return self.fetchedResultsController.fetchedObjects?.first as? T
+    }
+    
+    /**
+    Returns `true` if the `NSManagedObject` instance being observed still exists, or `false` if the object was already deleted.
+    */
+    public var isObjectDeleted: Bool {
+        
+        return self.object?.managedObjectContext == nil
+    }
+    
+    /**
+    Registers a `ManagedObjectObserver` to be notified when changes to the receiver's `object` are made.
+    
+    To prevent retain-cycles, `ManagedObjectController` only keeps `weak` references to its observers.
+    
+    For thread safety, this method needs to be called from the main thread. An assertion failure will occur (on debug builds only) if called from any thread other than the main thread.
+    
+    Calling `addObserver(_:)` multiple times on the same observer is safe, as `ManagedObjectController` unregisters previous notifications to the observer before re-registering them.
+    
+    :param: observer a `ManagedObjectObserver` to send change notifications to
+    */
+    public func addObserver<U: ManagedObjectObserver where U.EntityType == T>(observer: U) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to add an observer of type \(typeName(observer)) outside the main thread.")
+        
+        self.removeObserver(observer)
+        
+        self.registerChangeNotification(
+            &NotificationKey.willChangeObject,
+            name: ManagedObjectListControllerWillChangeObjectNotification,
+            toObserver: observer,
+            callback: { [weak self, weak observer] (objectController) -> Void in
+                
+                if let strongSelf = self, let object = strongSelf.object, let observer = observer {
+                    
+                    observer.managedObjectWillUpdate(objectController, object: object)
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didDeleteObject,
+            name: ManagedObjectListControllerDidDeleteObjectNotification,
+            toObserver: observer,
+            callback: { [weak self, weak observer] (objectController, object) -> Void in
+                
+                if let strongSelf = self, let observer = observer {
+                    
+                    observer.managedObjectWasDeleted(objectController, object: object)
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didUpdateObject,
+            name: ManagedObjectListControllerDidUpdateObjectNotification,
+            toObserver: observer,
+            callback: { [weak self, weak observer] (objectController, object) -> Void in
+                
+                if let strongSelf = self, let observer = observer {
+                    
+                    let previousCommitedAttributes = strongSelf.lastCommittedAttributes
+                    let currentCommitedAttributes = object.committedValuesForKeys(nil) as! [NSString: NSObject]
+                    
+                    var changedKeys = Set<String>()
+                    for key in currentCommitedAttributes.keys {
+                        
+                        if previousCommitedAttributes[key] != currentCommitedAttributes[key] {
+                            
+                            changedKeys.insert(key as String)
+                        }
+                    }
+                    
+                    strongSelf.lastCommittedAttributes = currentCommitedAttributes
+                    observer.managedObjectWasUpdated(
+                        objectController,
+                        object: object,
+                        changedPersistentKeys: changedKeys
+                    )
+                }
+            }
+        )
+    }
+    
+    /**
+    Unregisters a `ManagedObjectObserver` from receiving notifications for changes to the receiver's `object`.
+    
+    For thread safety, this method needs to be called from the main thread. An assertion failure will occur (on debug builds only) if called from any thread other than the main thread.
+    
+    :param: observer a `ManagedObjectObserver` to unregister notifications to
+    */
+    public func removeObserver<U: ManagedObjectObserver where U.EntityType == T>(observer: U) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to remove an observer of type \(typeName(observer)) outside the main thread.")
+        
+        let nilValue: AnyObject? = nil
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.willChangeObject, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didDeleteObject, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didUpdateObject, inObject: observer)
+    }
+    
+    
+    // MARK: Internal
+    
+    internal init(dataStack: DataStack, object: T) {
+        
+        let context = dataStack.mainContext
+        
+        let fetchRequest = NSFetchRequest()
+        fetchRequest.entity = context.entityDescriptionForEntityClass(T.self)
+        fetchRequest.fetchLimit = 1
+        fetchRequest.resultType = .ManagedObjectResultType
+        fetchRequest.sortDescriptors = []
+        
+        let originalObjectID = object.objectID
+        Where("SELF", isEqualTo: originalObjectID).applyToFetchRequest(fetchRequest)
+        
+        let fetchedResultsController = NSFetchedResultsController(
+            fetchRequest: fetchRequest,
+            managedObjectContext: context,
+            sectionNameKeyPath: nil,
+            cacheName: nil
+        )
+        
+        let fetchedResultsControllerDelegate = FetchedResultsControllerDelegate()
+        
+        self.originalObjectID = originalObjectID
+        self.fetchedResultsController = fetchedResultsController
+        self.fetchedResultsControllerDelegate = fetchedResultsControllerDelegate
+        self.parentStack = dataStack
+        
+        fetchedResultsControllerDelegate.handler = self
+        fetchedResultsControllerDelegate.fetchedResultsController = fetchedResultsController
+        
+        var error: NSError?
+        if !fetchedResultsController.performFetch(&error) {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed to perform fetch on <\(NSFetchedResultsController.self)>.")
+        }
+        
+        self.lastCommittedAttributes = (self.object?.committedValuesForKeys(nil) as? [NSString: NSObject]) ?? [:]
+    }
+    
+    
+    // MARK: Private
+    
+    private let originalObjectID: NSManagedObjectID
+    private let fetchedResultsController: NSFetchedResultsController
+    private let fetchedResultsControllerDelegate: FetchedResultsControllerDelegate
+    private var lastCommittedAttributes = [NSString: NSObject]()
+    private weak var parentStack: DataStack?
+    
+    private func registerChangeNotification(notificationKey: UnsafePointer<Void>, name: String, toObserver observer: AnyObject, callback: (objectController: ManagedObjectController<T>) -> Void) {
+        
+        setAssociatedRetainedObject(
+            NotificationObserver(
+                notificationName: name,
+                object: self,
+                closure: { [weak self] (note) -> Void in
+                    
+                    if let strongSelf = self {
+                        
+                        callback(objectController: strongSelf)
+                    }
+                }
+            ),
+            forKey: notificationKey,
+            inObject: observer
+        )
+    }
+    
+    private func registerObjectNotification(notificationKey: UnsafePointer<Void>, name: String, toObserver observer: AnyObject, callback: (objectController: ManagedObjectController<T>, object: T) -> Void) {
+        
+        setAssociatedRetainedObject(
+            NotificationObserver(
+                notificationName: name,
+                object: self,
+                closure: { [weak self] (note) -> Void in
+                    
+                    if let strongSelf = self,
+                        let userInfo = note.userInfo,
+                        let object = userInfo[UserInfoKeyObject] as? T {
+                            
+                            callback(
+                                objectController: strongSelf,
+                                object: object
+                            )
+                    }
+                }
+            ),
+            forKey: notificationKey,
+            inObject: observer
+        )
+    }
+}
+
+
+// MARK: - ManagedObjectController: FetchedResultsControllerHandler
+
+extension ManagedObjectController: FetchedResultsControllerHandler {
+    
+    // MARK: FetchedResultsControllerHandler
+    
+    private func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
+        
+        switch type {
+            
+        case .Delete:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidDeleteObjectNotification,
+                object: self,
+                userInfo: [UserInfoKeyObject: anObject]
+            )
+            
+        case .Update:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidUpdateObjectNotification,
+                object: self,
+                userInfo: [UserInfoKeyObject: anObject]
+            )
+            
+        default:
+            break
+        }
+    }
+    
+    private func controllerWillChangeContent(controller: NSFetchedResultsController) {
+        
+        NSNotificationCenter.defaultCenter().postNotificationName(
+            ManagedObjectListControllerWillChangeObjectNotification,
+            object: self
+        )
+    }
+}
+
+
+// MARK: - FetchedResultsControllerHandler
+
+private protocol FetchedResultsControllerHandler: class {
+    
+    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?)
+    
+    func controllerWillChangeContent(controller: NSFetchedResultsController)
+}
+
+
+// MARK: - FetchedResultsControllerDelegate
+
+private final class FetchedResultsControllerDelegate: NSFetchedResultsControllerDelegate {
+    
+    // MARK: NSFetchedResultsControllerDelegate
+    
+    @objc func controllerWillChangeContent(controller: NSFetchedResultsController) {
+        
+        self.handler?.controllerWillChangeContent(controller)
+    }
+    
+    @objc func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
+        
+        self.handler?.controller(controller, didChangeObject: anObject, atIndexPath: indexPath, forChangeType: type, newIndexPath: newIndexPath)
+    }
+    
+    
+    // MARK: Private
+    
+    weak var handler: FetchedResultsControllerHandler?
+    weak var fetchedResultsController: NSFetchedResultsController? {
+        
+        didSet {
+            
+            oldValue?.delegate = nil
+            self.fetchedResultsController?.delegate = self
+        }
+    }
+    
+    deinit {
+        
+        self.fetchedResultsController?.delegate = nil
+    }
+}

CoreStore/Observing/ManagedObjectListController.swift

@@ -0,0 +1,832 @@
+//
+//  ManagedObjectListController.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - SectionedBy
+
+/**
+The `SectionedBy` clause indicates the key path to use to group the `ManagedObjectListController` objects into sections. An optional closure can also be provided to transform the value into an appropriate section name:
+
+    let listController = CoreStore.observeSectionedList(
+        From(MyPersonEntity),
+        SectionedBy("age") { "Age \($0)" },
+        OrderBy(.Ascending("lastName"))
+    )
+*/
+public struct SectionedBy {
+    
+    // MARK: Public
+    
+    /**
+    Initializes a `SectionedBy` clause with the key path to use to group `ManagedObjectListController` objects into sections
+    
+    :param: sectionKeyPath the key path to use to group the objects into sections
+    */
+    public init(_ sectionKeyPath: KeyPath) {
+        
+        self.init(sectionKeyPath, { $0 })
+    }
+    
+    /**
+    Initializes a `SectionedBy` clause with the key path to use to group `ManagedObjectListController` objects into sections, and a closure to transform the value for the key path to an appropriate section name
+    
+    :param: sectionKeyPath the key path to use to group the objects into sections
+    :param: sectionIndexTransformer a closure to transform the value for the key path to an appropriate section name
+    */
+    public init(_ sectionKeyPath: KeyPath, _ sectionIndexTransformer: (sectionName: String?) -> String?) {
+        
+        self.sectionKeyPath = sectionKeyPath
+        self.sectionIndexTransformer = sectionIndexTransformer
+    }
+    
+    
+    // MARK: Internal
+    
+    internal let sectionKeyPath: KeyPath
+    internal let sectionIndexTransformer: (sectionName: KeyPath?) -> String?
+}
+
+
+// MARK: - ManagedObjectListController
+
+/**
+The `ManagedObjectListController` monitors changes to a list of `NSManagedObject` instances. Observers that implement the `ManagedObjectListChangeObserver` protocol may then register themselves to the `ManagedObjectListController`'s `addObserver(_:)` method:
+
+    let listController = CoreStore.observeObjectList(
+        From(MyPersonEntity),
+        Where("title", isEqualTo: "Engineer"),
+        OrderBy(.Ascending("lastName"))
+    )
+    listController.addObserver(self)
+
+The `ManagedObjectListController` instance needs to be held on (retained) for as long as the list needs to be observed.
+Observers registered via `addObserver(_:)` are not retained. `ManagedObjectListController` only keeps a `weak` reference to all observers, thus keeping itself free from retain-cycles.
+
+Lists created with `observeObjectList(...)` keep a single-section list of objects, where each object can be accessed by index:
+
+    let firstPerson: MyPersonEntity = listController[0]
+
+Accessing the list with an index above the valid range will throw an exception.
+
+Creating a sectioned-list is also possible with the `observeSectionedList(...)` method:
+
+    let listController = CoreStore.observeSectionedList(
+        From(MyPersonEntity),
+        SectionedBy("age") { "Age \($0)" },
+        Where("title", isEqualTo: "Engineer"),
+        OrderBy(.Ascending("lastName"))
+    )
+    listController.addObserver(self)
+
+Objects from `ManagedObjectListController`'s created this way can be accessed either by an `NSIndexPath` or a tuple:
+
+    let indexPath = NSIndexPath(forItem: 3, inSection: 2)
+    let person1 = listController[indexPath]
+    let person2 = listController[2, 3]
+
+In the example above, both `person1` and `person2` will contain the object at section=2, index=3.
+*/
+public final class ManagedObjectListController<T: NSManagedObject> {
+    
+    // MARK: Public
+    
+    /**
+    Accesses the object at the given index within the first section. This subscript indexer is typically used for `ManagedObjectListController`'s created with `addObserver(_:)`.
+    
+    :param: index the index of the object. Using an index above the valid range will throw an exception.
+    */
+    public subscript(index: Int) -> T {
+        
+        return self.fetchedResultsController.objectAtIndexPath(NSIndexPath(forItem: index, inSection: 0)) as! T
+    }
+    
+    /**
+    Accesses the object at the given `NSIndexPath`. This subscript indexer is typically used for `ManagedObjectListController`'s created with `observeSectionedList(_:)`.
+    
+    :param: indexPath the `NSIndexPath` for the object. Using an `indexPath` with an invalid range will throw an exception.
+    */
+    public subscript(indexPath: NSIndexPath) -> T {
+        
+        return self.fetchedResultsController.objectAtIndexPath(indexPath) as! T
+    }
+    
+    /**
+    Accesses the object at the given `sectionIndex` and `itemIndex`. This subscript indexer is typically used for `ManagedObjectListController`'s created with `observeSectionedList(_:)`.
+    
+    :param: sectionIndex the section index for the object. Using a `sectionIndex` with an invalid range will throw an exception.
+    :param: itemIndex the index for the object within the section. Using an `itemIndex` with an invalid range will throw an exception.
+    */
+    public subscript(sectionIndex: Int, itemIndex: Int) -> T {
+        
+        return self.fetchedResultsController.objectAtIndexPath(NSIndexPath(forItem: itemIndex, inSection: sectionIndex)) as! T
+    }
+    
+    /**
+    Returns the number of sections
+    */
+    public func numberOfSections() -> Int {
+        
+        return self.fetchedResultsController.sections?.count ?? 0
+    }
+    
+    /**
+    Returns the number of objects in the specified section
+    
+    :param: section the section index
+    */
+    public func numberOfObjectsInSection(section: Int) -> Int {
+        
+        return (self.fetchedResultsController.sections?[section] as? NSFetchedResultsSectionInfo)?.numberOfObjects ?? 0
+    }
+    
+    /**
+    Returns the `NSFetchedResultsSectionInfo` for the specified section
+    
+    :param: section the section index
+    */
+    public func sectionInfoAtIndex(section: Int) -> NSFetchedResultsSectionInfo {
+        
+        return self.fetchedResultsController.sections![section] as! NSFetchedResultsSectionInfo
+    }
+    
+    /**
+    Registers a `ManagedObjectListChangeObserver` to be notified when changes to the receiver's list occur.
+    
+    To prevent retain-cycles, `ManagedObjectListController` only keeps `weak` references to its observers.
+    
+    For thread safety, this method needs to be called from the main thread. An assertion failure will occur (on debug builds only) if called from any thread other than the main thread.
+    
+    Calling `addObserver(_:)` multiple times on the same observer is safe, as `ManagedObjectListController` unregisters previous notifications to the observer before re-registering them.
+    
+    :param: observer a `ManagedObjectListChangeObserver` to send change notifications to
+    */
+    public func addObserver<U: ManagedObjectListChangeObserver where U.EntityType == T>(observer: U) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to add an observer of type \(typeName(observer)) outside the main thread.")
+        
+        self.removeObserver(observer)
+        
+        self.registerChangeNotification(
+            &NotificationKey.willChangeList,
+            name: ManagedObjectListControllerWillChangeListNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectListWillChange(listController)
+                }
+            }
+        )
+        self.registerChangeNotification(
+            &NotificationKey.didChangeList,
+            name: ManagedObjectListControllerDidChangeListNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectListDidChange(listController)
+                }
+            }
+        )
+    }
+    
+    /**
+    Registers a `ManagedObjectListObjectObserver` to be notified when changes to the receiver's list occur.
+    
+    To prevent retain-cycles, `ManagedObjectListController` only keeps `weak` references to its observers.
+    
+    For thread safety, this method needs to be called from the main thread. An assertion failure will occur (on debug builds only) if called from any thread other than the main thread.
+    
+    Calling `addObserver(_:)` multiple times on the same observer is safe, as `ManagedObjectListController` unregisters previous notifications to the observer before re-registering them.
+    
+    :param: observer a `ManagedObjectListObjectObserver` to send change notifications to
+    */
+    public func addObserver<U: ManagedObjectListObjectObserver where U.EntityType == T>(observer: U) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to add an observer of type \(typeName(observer)) outside the main thread.")
+        
+        self.removeObserver(observer)
+        
+        self.registerChangeNotification(
+            &NotificationKey.willChangeList,
+            name: ManagedObjectListControllerWillChangeListNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectListWillChange(listController)
+                }
+            }
+        )
+        self.registerChangeNotification(
+            &NotificationKey.didChangeList,
+            name: ManagedObjectListControllerDidChangeListNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectListDidChange(listController)
+                }
+            }
+        )
+        
+        self.registerObjectNotification(
+            &NotificationKey.didInsertObject,
+            name: ManagedObjectListControllerDidInsertObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didInsertObject: object,
+                        toIndexPath: newIndexPath!
+                    )
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didDeleteObject,
+            name: ManagedObjectListControllerDidDeleteObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didDeleteObject: object,
+                        fromIndexPath: indexPath!
+                    )
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didUpdateObject,
+            name: ManagedObjectListControllerDidUpdateObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didUpdateObject: object,
+                        atIndexPath: indexPath!
+                    )
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didMoveObject,
+            name: ManagedObjectListControllerDidMoveObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didMoveObject: object,
+                        fromIndexPath: indexPath!,
+                        toIndexPath: newIndexPath!
+                    )
+                }
+            }
+        )
+    }
+    
+    /**
+    Registers a `ManagedObjectListSectionObserver` to be notified when changes to the receiver's list occur.
+    
+    To prevent retain-cycles, `ManagedObjectListController` only keeps `weak` references to its observers.
+    
+    For thread safety, this method needs to be called from the main thread. An assertion failure will occur (on debug builds only) if called from any thread other than the main thread.
+    
+    Calling `addObserver(_:)` multiple times on the same observer is safe, as `ManagedObjectListController` unregisters previous notifications to the observer before re-registering them.
+    
+    :param: observer a `ManagedObjectListSectionObserver` to send change notifications to
+    */
+    public func addObserver<U: ManagedObjectListSectionObserver where U.EntityType == T>(observer: U) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to add an observer of type \(typeName(observer)) outside the main thread.")
+        
+        self.removeObserver(observer)
+        
+        self.registerChangeNotification(
+            &NotificationKey.willChangeList,
+            name: ManagedObjectListControllerWillChangeListNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectListWillChange(listController)
+                }
+            }
+        )
+        self.registerChangeNotification(
+            &NotificationKey.didChangeList,
+            name: ManagedObjectListControllerDidChangeListNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectListDidChange(listController)
+                }
+            }
+        )
+        
+        self.registerObjectNotification(
+            &NotificationKey.didInsertObject,
+            name: ManagedObjectListControllerDidInsertObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didInsertObject: object,
+                        toIndexPath: newIndexPath!
+                    )
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didDeleteObject,
+            name: ManagedObjectListControllerDidDeleteObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didDeleteObject: object,
+                        fromIndexPath: indexPath!
+                    )
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didUpdateObject,
+            name: ManagedObjectListControllerDidUpdateObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didUpdateObject: object,
+                        atIndexPath: indexPath!
+                    )
+                }
+            }
+        )
+        self.registerObjectNotification(
+            &NotificationKey.didMoveObject,
+            name: ManagedObjectListControllerDidMoveObjectNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, object, indexPath, newIndexPath) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didMoveObject: object,
+                        fromIndexPath: indexPath!,
+                        toIndexPath: newIndexPath!
+                    )
+                }
+            }
+        )
+        
+        self.registerSectionNotification(
+            &NotificationKey.didInsertSection,
+            name: ManagedObjectListControllerDidInsertSectionNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, sectionInfo, sectionIndex) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didInsertSection: sectionInfo,
+                        toSectionIndex: sectionIndex
+                    )
+                }
+            }
+        )
+        self.registerSectionNotification(
+            &NotificationKey.didDeleteSection,
+            name: ManagedObjectListControllerDidDeleteSectionNotification,
+            toObserver: observer,
+            callback: { [weak observer] (listController, sectionInfo, sectionIndex) -> Void in
+                
+                if let observer = observer {
+                    
+                    observer.managedObjectList(
+                        listController,
+                        didDeleteSection: sectionInfo,
+                        fromSectionIndex: sectionIndex
+                    )
+                }
+            }
+        )
+    }
+    
+    /**
+    Unregisters a `ManagedObjectListChangeObserver` from receiving notifications for changes to the receiver's list.
+    
+    For thread safety, this method needs to be called from the main thread. An assertion failure will occur (on debug builds only) if called from any thread other than the main thread.
+    
+    :param: observer a `ManagedObjectListChangeObserver` to unregister notifications to
+    */
+    public func removeObserver<U: ManagedObjectListChangeObserver where U.EntityType == T>(observer: U) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to remove an observer of type \(typeName(observer)) outside the main thread.")
+        
+        let nilValue: AnyObject? = nil
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.willChangeList, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didChangeList, inObject: observer)
+        
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didInsertObject, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didDeleteObject, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didUpdateObject, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didMoveObject, inObject: observer)
+        
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didInsertSection, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &NotificationKey.didDeleteSection, inObject: observer)
+    }
+    
+    
+    // MARK: Internal
+    
+    internal init(dataStack: DataStack, from: From<T>, sectionedBy: SectionedBy?, fetchClauses: [FetchClause]) {
+        
+        let context = dataStack.mainContext
+        
+        let fetchRequest = NSFetchRequest()
+        from.applyToFetchRequest(fetchRequest, context: context)
+        
+        fetchRequest.fetchLimit = 0
+        fetchRequest.resultType = .ManagedObjectResultType
+        
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        let fetchedResultsController = NSFetchedResultsController(
+            fetchRequest: fetchRequest,
+            managedObjectContext: context,
+            sectionNameKeyPath: sectionedBy?.sectionKeyPath,
+            cacheName: nil
+        )
+        
+        let fetchedResultsControllerDelegate = FetchedResultsControllerDelegate()
+        
+        self.fetchedResultsController = fetchedResultsController
+        self.fetchedResultsControllerDelegate = fetchedResultsControllerDelegate
+        self.parentStack = dataStack
+        
+        if let sectionIndexTransformer = sectionedBy?.sectionIndexTransformer {
+            
+            self.sectionIndexTransformer = sectionIndexTransformer
+        }
+        else {
+            
+            self.sectionIndexTransformer = { $0 }
+        }
+        
+        
+        fetchedResultsControllerDelegate.handler = self
+        fetchedResultsControllerDelegate.fetchedResultsController = fetchedResultsController
+        
+        var error: NSError?
+        if !fetchedResultsController.performFetch(&error) {
+            
+            CoreStore.handleError(
+                error ?? NSError(coreStoreErrorCode: .UnknownError),
+                "Failed to perform fetch on <\(NSFetchedResultsController.self)>.")
+        }
+    }
+    
+    
+    // MARK: Private
+    
+    private let fetchedResultsController: NSFetchedResultsController
+    private let fetchedResultsControllerDelegate: FetchedResultsControllerDelegate
+    private let sectionIndexTransformer: (sectionName: KeyPath?) -> String?
+    private weak var parentStack: DataStack?
+    
+    private func registerChangeNotification(notificationKey: UnsafePointer<Void>, name: String, toObserver observer: AnyObject, callback: (listController: ManagedObjectListController<T>) -> Void) {
+        
+        setAssociatedRetainedObject(
+            NotificationObserver(
+                notificationName: name,
+                object: self,
+                closure: { [weak self] (note) -> Void in
+                    
+                    if let strongSelf = self {
+                        
+                        callback(listController: strongSelf)
+                    }
+                }
+            ),
+            forKey: notificationKey,
+            inObject: observer
+        )
+    }
+    
+    private func registerObjectNotification(notificationKey: UnsafePointer<Void>, name: String, toObserver observer: AnyObject, callback: (listController: ManagedObjectListController<T>, object: T, indexPath: NSIndexPath?, newIndexPath: NSIndexPath?) -> Void) {
+        
+        setAssociatedRetainedObject(
+            NotificationObserver(
+                notificationName: name,
+                object: self,
+                closure: { [weak self] (note) -> Void in
+                    
+                    if let strongSelf = self,
+                        let userInfo = note.userInfo,
+                        let object = userInfo[UserInfoKeyObject] as? T {
+                            
+                            callback(
+                                listController: strongSelf,
+                                object: object,
+                                indexPath: userInfo[UserInfoKeyIndexPath] as? NSIndexPath,
+                                newIndexPath: userInfo[UserInfoKeyNewIndexPath] as? NSIndexPath
+                            )
+                    }
+                }
+            ),
+            forKey: notificationKey,
+            inObject: observer
+        )
+    }
+    
+    private func registerSectionNotification(notificationKey: UnsafePointer<Void>, name: String, toObserver observer: AnyObject, callback: (listController: ManagedObjectListController<T>, sectionInfo: NSFetchedResultsSectionInfo, sectionIndex: Int) -> Void) {
+        
+        setAssociatedRetainedObject(
+            NotificationObserver(
+                notificationName: name,
+                object: self,
+                closure: { [weak self] (note) -> Void in
+                    
+                    if let strongSelf = self,
+                        let userInfo = note.userInfo,
+                        let sectionInfo = userInfo[UserInfoKeySectionInfo] as? NSFetchedResultsSectionInfo,
+                        let sectionIndex = (userInfo[UserInfoKeySectionIndex] as? NSNumber)?.integerValue {
+                            
+                            callback(
+                                listController: strongSelf,
+                                sectionInfo: sectionInfo,
+                                sectionIndex: sectionIndex
+                            )
+                    }
+                }
+            ),
+            forKey: notificationKey,
+            inObject: observer
+        )
+    }
+}
+
+
+// MARK: - ManagedObjectListController: FetchedResultsControllerHandler
+
+extension ManagedObjectListController: FetchedResultsControllerHandler {
+    
+    // MARK: FetchedResultsControllerHandler
+    
+    private func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
+        
+        switch type {
+            
+        case .Insert:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidInsertObjectNotification,
+                object: self,
+                userInfo: [
+                    UserInfoKeyObject: anObject,
+                    UserInfoKeyNewIndexPath: newIndexPath!
+                ]
+            )
+            
+        case .Delete:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidDeleteObjectNotification,
+                object: self,
+                userInfo: [
+                    UserInfoKeyObject: anObject,
+                    UserInfoKeyIndexPath: indexPath!
+                ]
+            )
+            
+        case .Update:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidUpdateObjectNotification,
+                object: self,
+                userInfo: [
+                    UserInfoKeyObject: anObject,
+                    UserInfoKeyIndexPath: indexPath!
+                ]
+            )
+            
+        case .Move:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidMoveObjectNotification,
+                object: self,
+                userInfo: [
+                    UserInfoKeyObject: anObject,
+                    UserInfoKeyIndexPath: indexPath!,
+                    UserInfoKeyNewIndexPath: newIndexPath!
+                ]
+            )
+        }
+    }
+    
+    private func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
+        
+        switch type {
+            
+        case .Insert:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidInsertSectionNotification,
+                object: self,
+                userInfo: [
+                    UserInfoKeySectionInfo: sectionInfo,
+                    UserInfoKeySectionIndex: NSNumber(integer: sectionIndex)
+                ]
+            )
+            
+        case .Delete:
+            NSNotificationCenter.defaultCenter().postNotificationName(
+                ManagedObjectListControllerDidDeleteSectionNotification,
+                object: self,
+                userInfo: [
+                    UserInfoKeySectionInfo: sectionInfo,
+                    UserInfoKeySectionIndex: NSNumber(integer: sectionIndex)
+                ]
+            )
+            
+        default:
+            break
+        }
+    }
+    
+    private func controllerWillChangeContent(controller: NSFetchedResultsController) {
+        
+        NSNotificationCenter.defaultCenter().postNotificationName(
+            ManagedObjectListControllerWillChangeListNotification,
+            object: self
+        )
+    }
+    
+    private func controllerDidChangeContent(controller: NSFetchedResultsController) {
+        
+        NSNotificationCenter.defaultCenter().postNotificationName(
+            ManagedObjectListControllerDidChangeListNotification,
+            object: self
+        )
+    }
+    
+    private func controller(controller: NSFetchedResultsController, sectionIndexTitleForSectionName sectionName: String?) -> String? {
+        
+        return self.sectionIndexTransformer(sectionName: sectionName)
+    }
+}
+
+
+// MARK: - FetchedResultsControllerHandler
+
+private protocol FetchedResultsControllerHandler: class {
+    
+    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?)
+    
+    func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType)
+    
+    func controllerWillChangeContent(controller: NSFetchedResultsController)
+    
+    func controllerDidChangeContent(controller: NSFetchedResultsController)
+    
+    func controller(controller: NSFetchedResultsController, sectionIndexTitleForSectionName sectionName: String?) -> String?
+}
+
+
+// MARK: - FetchedResultsControllerDelegate
+
+private final class FetchedResultsControllerDelegate: NSFetchedResultsControllerDelegate {
+    
+    // MARK: NSFetchedResultsControllerDelegate
+    
+    @objc func controllerWillChangeContent(controller: NSFetchedResultsController) {
+        
+        self.handler?.controllerWillChangeContent(controller)
+    }
+    
+    @objc func controllerDidChangeContent(controller: NSFetchedResultsController) {
+        
+        self.handler?.controllerDidChangeContent(controller)
+    }
+    
+    @objc func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
+        
+        self.handler?.controller(controller, didChangeObject: anObject, atIndexPath: indexPath, forChangeType: type, newIndexPath: newIndexPath)
+    }
+    
+    @objc func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
+        
+        self.handler?.controller(controller, didChangeSection: sectionInfo, atIndex: sectionIndex, forChangeType: type)
+    }
+    
+    @objc func controller(controller: NSFetchedResultsController, sectionIndexTitleForSectionName sectionName: String?) -> String? {
+        
+        return self.handler?.controller(controller, sectionIndexTitleForSectionName: sectionName)
+    }
+    
+    
+    // MARK: Private
+    
+    weak var handler: FetchedResultsControllerHandler?
+    weak var fetchedResultsController: NSFetchedResultsController? {
+        
+        didSet {
+            
+            oldValue?.delegate = nil
+            self.fetchedResultsController?.delegate = self
+        }
+    }
+    
+    deinit {
+        
+        self.fetchedResultsController?.delegate = nil
+    }
+}
+
+
+private let ManagedObjectListControllerWillChangeListNotification = "ManagedObjectListControllerWillChangeListNotification"
+private let ManagedObjectListControllerDidChangeListNotification = "ManagedObjectListControllerDidChangeListNotification"
+
+private let ManagedObjectListControllerDidInsertObjectNotification = "ManagedObjectListControllerDidInsertObjectNotification"
+private let ManagedObjectListControllerDidDeleteObjectNotification = "ManagedObjectListControllerDidDeleteObjectNotification"
+private let ManagedObjectListControllerDidUpdateObjectNotification = "ManagedObjectListControllerDidUpdateObjectNotification"
+private let ManagedObjectListControllerDidMoveObjectNotification = "ManagedObjectListControllerDidMoveObjectNotification"
+
+private let ManagedObjectListControllerDidInsertSectionNotification = "ManagedObjectListControllerDidInsertSectionNotification"
+private let ManagedObjectListControllerDidDeleteSectionNotification = "ManagedObjectListControllerDidDeleteSectionNotification"
+
+private let UserInfoKeyObject = "UserInfoKeyObject"
+private let UserInfoKeyIndexPath = "UserInfoKeyIndexPath"
+private let UserInfoKeyNewIndexPath = "UserInfoKeyNewIndexPath"
+
+private let UserInfoKeySectionInfo = "UserInfoKeySectionInfo"
+private let UserInfoKeySectionIndex = "UserInfoKeySectionIndex"
+
+private struct NotificationKey {
+    
+    static var willChangeList: Void?
+    static var didChangeList: Void?
+    
+    static var didInsertObject: Void?
+    static var didDeleteObject: Void?
+    static var didUpdateObject: Void?
+    static var didMoveObject: Void?
+    
+    static var didInsertSection: Void?
+    static var didDeleteSection: Void?
+}

CoreStore/Observing/ManagedObjectListObserver.swift

@@ -0,0 +1,147 @@
+//
+//  ManagedObjectListObserver.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - ManagedObjectListChangeObserver
+
+/**
+Implement the `ManagedObjectListChangeObserver` protocol to observe changes to a list of `NSManagedObject`'s. `ManagedObjectListChangeObserver`'s may register themselves to a `ManagedObjectListController`'s `addObserver(_:)` method:
+
+    let listController = CoreStore.observeObjectList(
+        From(MyPersonEntity),
+        OrderBy(.Ascending("lastName"))
+    )
+    listController.addObserver(self)
+*/
+public protocol ManagedObjectListChangeObserver: class {
+    
+    /**
+    The `NSManagedObject` type for the observed list
+    */
+    typealias EntityType: NSManagedObject
+    
+    /**
+    Handles processing just before a change to the observed list occurs
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    */
+    func managedObjectListWillChange(listController: ManagedObjectListController<EntityType>)
+    
+    /**
+    Handles processing right after a change to the observed list occurs
+    
+    :param: listController the `ManagedObjectListController` monitoring the object being observed
+    */
+    func managedObjectListDidChange(listController: ManagedObjectListController<EntityType>)
+}
+
+
+// MARK: - ManagedObjectListObjectObserver
+
+/**
+Implement the `ManagedObjectListObjectObserver` protocol to observe detailed changes to a list's object. `ManagedObjectListObjectObserver`'s may register themselves to a `ManagedObjectListController`'s `addObserver(_:)` method:
+
+    let listController = CoreStore.observeObjectList(
+        From(MyPersonEntity),
+        OrderBy(.Ascending("lastName"))
+    )
+    listController.addObserver(self)
+*/
+public protocol ManagedObjectListObjectObserver: ManagedObjectListChangeObserver {
+    
+    /**
+    Notifies that an object was inserted to the specified `NSIndexPath` in the list
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    :param: object the entity type for the inserted object
+    :param: indexPath the new `NSIndexPath` for the inserted object
+    */
+    func managedObjectList(listController: ManagedObjectListController<EntityType>, didInsertObject object: EntityType, toIndexPath indexPath: NSIndexPath)
+    
+    /**
+    Notifies that an object was deleted from the specified `NSIndexPath` in the list
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    :param: object the entity type for the deleted object
+    :param: indexPath the `NSIndexPath` for the deleted object
+    */
+    func managedObjectList(listController: ManagedObjectListController<EntityType>, didDeleteObject object: EntityType, fromIndexPath indexPath: NSIndexPath)
+    
+    /**
+    Notifies that an object at the specified `NSIndexPath` was updated
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    :param: object the entity type for the updated object
+    :param: indexPath the `NSIndexPath` for the updated object
+    */
+    func managedObjectList(listController: ManagedObjectListController<EntityType>, didUpdateObject object: EntityType, atIndexPath indexPath: NSIndexPath)
+    
+    /**
+    Notifies that an object's index changed
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    :param: object the entity type for the moved object
+    :param: fromIndexPath the previous `NSIndexPath` for the moved object
+    :param: toIndexPath the new `NSIndexPath` for the moved object
+    */
+    func managedObjectList(listController: ManagedObjectListController<EntityType>, didMoveObject object: EntityType, fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath)
+}
+
+
+// MARK: - ManagedObjectListSectionObserver
+
+/**
+Implement the `ManagedObjectListSectionObserver` protocol to observe changes to a list's section info. `ManagedObjectListSectionObserver`'s may register themselves to a `ManagedObjectListController`'s `addObserver(_:)` method:
+
+    let listController = CoreStore.observeSectionedList(
+        From(MyPersonEntity),
+        SectionedBy("age") { "Age \($0)" },
+        OrderBy(.Ascending("lastName"))
+    )
+    listController.addObserver(self)
+*/
+public protocol ManagedObjectListSectionObserver: ManagedObjectListObjectObserver {
+    
+    /**
+    Notifies that a section was inserted at the specified index
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    :param: sectionInfo the `NSFetchedResultsSectionInfo` for the inserted section
+    :param: sectionIndex the new section index for the new section
+    */
+    func managedObjectList(listController: ManagedObjectListController<EntityType>, didInsertSection sectionInfo: NSFetchedResultsSectionInfo, toSectionIndex sectionIndex: Int)
+    
+    /**
+    Notifies that a section was inserted at the specified index
+    
+    :param: listController the `ManagedObjectListController` monitoring the list being observed
+    :param: sectionInfo the `NSFetchedResultsSectionInfo` for the deleted section
+    :param: sectionIndex the previous section index for the deleted section
+    */
+    func managedObjectList(listController: ManagedObjectListController<EntityType>, didDeleteSection sectionInfo: NSFetchedResultsSectionInfo, fromSectionIndex sectionIndex: Int)
+}

CoreStore/Observing/ManagedObjectObserver.swift

@@ -0,0 +1,69 @@
+//
+//  ManagedObjectObserver.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - ManagedObjectObserver
+
+/**
+Implement the `ManagedObjectObserver` protocol to observe changes to a single `NSManagedObject` instance. `ManagedObjectObserver`'s may register themselves to a `ManagedObjectController`'s `addObserver(_:)` method:
+
+    let objectController = CoreStore.observeObject(object)
+    objectController.addObserver(self)
+*/
+public protocol ManagedObjectObserver: class {
+    
+    /**
+    The `NSManagedObject` type for the observed object
+    */
+    typealias EntityType: NSManagedObject
+    
+    /**
+    Handles processing just before a change to the observed `object` occurs
+    
+    :param: objectController the `ManagedObjectController` monitoring the object being observed
+    :param: object the `NSManagedObject` instance being observed
+    */
+    func managedObjectWillUpdate(objectController: ManagedObjectController<EntityType>, object: EntityType)
+    
+    /**
+    Handles processing right after a change to the observed `object` occurs
+    
+    :param: objectController the `ManagedObjectController` monitoring the object being observed
+    :param: object the `NSManagedObject` instance being observed
+    :param: changedPersistentKeys a `Set` of key paths for the attributes that were changed. Note that `changedPersistentKeys` only contains keys for attributes/relationships present in the persistent store, thus transient properties will not be reported.
+    */
+    func managedObjectWasUpdated(objectController: ManagedObjectController<EntityType>, object: EntityType, changedPersistentKeys: Set<KeyPath>)
+    
+    /**
+    Handles processing right after `object` is deleted
+    
+    :param: objectController the `ManagedObjectController` monitoring the object being observed
+    :param: object the `NSManagedObject` instance being observed
+    */
+    func managedObjectWasDeleted(objectController: ManagedObjectController<EntityType>, object: EntityType)
+}

CoreStore/Saving and Processing/AsynchronousDataTransaction.swift

@@ -0,0 +1,180 @@
+//
+//  AsynchronousDataTransaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - AsynchronousDataTransaction
+
+/**
+The `AsynchronousDataTransaction` provides an interface for `NSManagedObject` creates, updates, and deletes. A transaction object should typically be only used from within a transaction block initiated from `DataStack.beginAsynchronous(_:)`, or from `CoreStore.beginAsynchronous(_:)`.
+*/
+public final class AsynchronousDataTransaction: BaseDataTransaction {
+    
+    // MARK: Public
+    
+    /**
+    Saves the transaction changes asynchronously. This method should not be used after the `commit()` method was already called once.
+    
+    :param: completion the block executed after the save completes. Success or failure is reported by the `SaveResult` argument of the block.
+    */
+    public func commit(completion: (result: SaveResult) -> Void) {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to commit a \(typeName(self)) outside its designated queue.")
+        CoreStore.assert(!self.isCommitted, "Attempted to commit a \(typeName(self)) more than once.")
+        
+        self.isCommitted = true
+        let semaphore = GCDSemaphore(0)
+        self.context.saveAsynchronouslyWithCompletion { (result) -> Void in
+            
+            self.result = result
+            completion(result: result)
+            semaphore.signal()
+        }
+        semaphore.wait()
+    }
+    
+    /**
+    Saves the transaction changes and waits for completion synchronously. This method should not be used after the `commit()` method was already called once.
+    */
+    public func commit() {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to commit a \(typeName(self)) outside its designated queue.")
+        CoreStore.assert(!self.isCommitted, "Attempted to commit a \(typeName(self)) more than once.")
+        
+        self.isCommitted = true
+        self.result = self.context.saveSynchronously()
+    }
+    
+    /**
+    Begins a child transaction synchronously where NSManagedObject creates, updates, and deletes can be made. This method should not be used after the `commit()` method was already called once.
+    
+    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent `NSManagedObjectContext`.
+    :returns: a `SaveResult` value indicating success or failure, or `nil` if the transaction was not comitted synchronously
+    */
+    public func beginSynchronous(closure: (transaction: SynchronousDataTransaction) -> Void) -> SaveResult? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to begin a child transaction from a \(typeName(self)) outside its designated queue.")
+        CoreStore.assert(!self.isCommitted, "Attempted to begin a child transaction from an already committed \(typeName(self)).")
+        
+        return SynchronousDataTransaction(
+            mainContext: self.context,
+            queue: self.childTransactionQueue,
+            closure: closure).performAndWait()
+    }
+    
+    
+    // MARK: BaseDataTransaction
+    
+    /**
+    Creates a new `NSManagedObject` with the specified entity type.
+    
+    :param: into the `Into` clause indicating the destination `NSManagedObject` entity type and the destination configuration
+    :returns: a new `NSManagedObject` instance of the specified entity type.
+    */
+    public override func create<T: NSManagedObject>(into: Into<T>) -> T {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to create an entity of type <\(T.self)> from an already committed \(typeName(self)).")
+        
+        return super.create(into)
+    }
+    
+    /**
+    Returns an editable proxy of a specified `NSManagedObject`. This method should not be used after the `commit()` method was already called once.
+    
+    :param: object the `NSManagedObject` type to be edited
+    :returns: an editable proxy for the specified `NSManagedObject`.
+    */
+    public override func fetch<T: NSManagedObject>(object: T?) -> T? {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to update an entity of type \(typeName(object)) from an already committed \(typeName(self)).")
+        
+        return super.fetch(object)
+    }
+    
+    /**
+    Deletes a specified `NSManagedObject`. This method should not be used after the `commit()` method was already called once.
+    
+    :param: object the `NSManagedObject` type to be deleted
+    */
+    public override func delete(object: NSManagedObject?) {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to delete an entity of type \(typeName(object)) from an already committed \(typeName(self)).")
+        
+        super.delete(object)
+    }
+    
+    /**
+    Rolls back the transaction by resetting the `NSManagedObjectContext`. After calling this method, all `NSManagedObjects` fetched within the transaction will become invalid. This method should not be used after the `commit()` method was already called once.
+    */
+    public override func rollback() {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to rollback an already committed \(typeName(self)).")
+        
+        super.rollback()
+    }
+    
+    
+    // MARK: Internal
+    
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue, closure: (transaction: AsynchronousDataTransaction) -> Void) {
+        
+        self.closure = closure
+        
+        super.init(mainContext: mainContext, queue: queue)
+    }
+    
+    internal func perform() {
+        
+        self.transactionQueue.async {
+            
+            self.closure(transaction: self)
+            if !self.isCommitted && self.hasChanges {
+                
+                CoreStore.log(.Warning, message: "The closure for the \(typeName(self)) completed without being committed. All changes made within the transaction were discarded.")
+            }
+        }
+    }
+    
+    internal func performAndWait() -> SaveResult? {
+        
+        self.transactionQueue.sync {
+            
+            self.closure(transaction: self)
+            if !self.isCommitted && self.hasChanges {
+                
+                CoreStore.log(.Warning, message: "The closure for the \(typeName(self)) completed without being committed. All changes made within the transaction were discarded.")
+            }
+        }
+        return self.result
+    }
+    
+    
+    // MARK: Private
+    
+    private let closure: (transaction: AsynchronousDataTransaction) -> Void
+}

CoreStore/Saving and Processing/BaseDataTransaction.swift

@@ -0,0 +1,237 @@
+//
+//  BaseDataTransaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - Into
+
+/**
+A `Into` clause contains the destination entity and destination persistent store for a `create(...)` method. A common usage is to just indicate the entity:
+
+    let person = transaction.create(Into(MyPersonEntity))
+
+For cases where multiple `NSPersistentStore`'s contain the same entity, the destination configuration's name needs to be specified as well:
+
+    let person = transaction.create(Into<MyPersonEntity>("Configuration1"))
+
+This helps the `NSManagedObjectContext` to determine which
+*/
+public struct Into<T: NSManagedObject> {
+    
+    // MARK: Public
+    
+    /**
+    Initializes an `Into` clause.
+    Sample Usage:
+    
+        let person = transaction.create(Into<MyPersonEntity>())
+    */
+    public init(){
+        
+        self.configuration = nil
+        self.inferStoreIfPossible = true
+    }
+    
+    /**
+    Initializes an `Into` clause with the specified entity type.
+    Sample Usage:
+    
+        let person = transaction.create(Into(MyPersonEntity))
+    
+    :param: entity the `NSManagedObject` type to be created
+    */
+    public init(_ entity: T.Type) {
+        
+        self.configuration = nil
+        self.inferStoreIfPossible = true
+    }
+    
+    /**
+    Initializes an `Into` clause with the specified configuration.
+    Sample Usage:
+    
+        let person = transaction.create(Into<MyPersonEntity>("Configuration1"))
+    
+    :param: configuration the `NSPersistentStore` configuration name to associate the object to. This parameter is required if multiple configurations contain the created `NSManagedObject`'s entity type. Set to `nil` to use the default configuration.
+    */
+    public init(_ configuration: String?) {
+        
+        self.configuration = configuration
+        self.inferStoreIfPossible = false
+    }
+    
+    /**
+    Initializes an `Into` clause with the specified entity type and configuration.
+    Sample Usage:
+    
+        let person = transaction.create(Into(MyPersonEntity.self, "Configuration1"))
+    
+    :param: entity the `NSManagedObject` type to be created
+    :param: configuration the `NSPersistentStore` configuration name to associate the object to. This parameter is required if multiple configurations contain the created `NSManagedObject`'s entity type. Set to `nil` to use the default configuration.
+    */
+    public init(_ entity: T.Type, _ configuration: String?) {
+        
+        self.configuration = configuration
+        self.inferStoreIfPossible = false
+    }
+    
+    
+    // MARK: Internal
+    
+    internal let configuration: String?
+    internal let inferStoreIfPossible: Bool
+}
+
+
+// MARK: - BaseDataTransaction
+
+/**
+The `BaseDataTransaction` is an abstract interface for `NSManagedObject` creates, updates, and deletes. All `BaseDataTransaction` subclasses manage a private `NSManagedObjectContext` which are direct children of the `NSPersistentStoreCoordinator`'s root `NSManagedObjectContext`. This means that all updates are saved first to the persistent store, and then propagated up to the read-only `NSManagedObjectContext`.
+*/
+public /*abstract*/ class BaseDataTransaction {
+    
+    // MARK: Object management
+    
+    /**
+    Indicates if the transaction has pending changes
+    */
+    public var hasChanges: Bool {
+        
+        return self.context.hasChanges
+    }
+    
+    /**
+    Creates a new `NSManagedObject` with the specified entity type.
+    
+    :param: into the `Into` clause indicating the destination `NSManagedObject` entity type and the destination configuration
+    :returns: a new `NSManagedObject` instance of the specified entity type.
+    */
+    public func create<T: NSManagedObject>(into: Into<T>) -> T {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to create an entity of type <\(T.self)> outside its designated queue.")
+        
+        let context = self.context
+        let object = T.createInContext(context)
+        
+        if into.inferStoreIfPossible {
+            
+            switch context.parentStack!.persistentStoreForEntityClass(T.self, configuration: nil, inferStoreIfPossible: true) {
+                
+            case (.Some(let persistentStore), _):
+                context.assignObject(object, toPersistentStore: persistentStore)
+                
+            case (.None, true):
+                CoreStore.assert(false, "Attempted to create an entity of type \(typeName(object)) with ambiguous destination persistent store, but the configuration name was not specified.")
+                
+            default:
+                CoreStore.assert(false, "Attempted to create an entity of type \(typeName(object)), but a destination persistent store containing the entity type could not be found.")
+            }
+        }
+        else {
+            
+            switch context.parentStack!.persistentStoreForEntityClass(T.self, configuration: into.configuration, inferStoreIfPossible: false) {
+                
+            case (.Some(let persistentStore), _):
+                context.assignObject(object, toPersistentStore: persistentStore)
+                
+            default:
+                if let configuration = into.configuration {
+                    
+                    CoreStore.assert(false, "Attempted to create an entity of type \(typeName(object)) into the configuration \"\(configuration)\", which it doesn't belong to.")
+                }
+                else {
+                    
+                    CoreStore.assert(false, "Attempted to create an entity of type \(typeName(object)) into the default configuration, which it doesn't belong to.")
+                }
+            }
+        }
+        
+        return object
+    }
+    
+    /**
+    Returns an editable proxy of a specified `NSManagedObject`.
+    
+    :param: object the `NSManagedObject` type to be edited
+    :returns: an editable proxy for the specified `NSManagedObject`.
+    */
+    public func fetch<T: NSManagedObject>(object: T?) -> T? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to update an entity of type \(typeName(object)) outside its designated queue.")
+        
+        return object?.inContext(self.context)
+    }
+    
+    /**
+    Deletes a specified `NSManagedObject`.
+    
+    :param: object the `NSManagedObject` type to be deleted
+    */
+    public func delete(object: NSManagedObject?) {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to delete an entity of type \(typeName(object)) outside its designated queue.")
+        
+        object?.inContext(self.context)?.deleteFromContext()
+    }
+    
+    // MARK: Saving changes
+    
+    /**
+    Rolls back the transaction by resetting the `NSManagedObjectContext`. After calling this method, all `NSManagedObjects` fetched within the transaction will become invalid.
+    */
+    public func rollback() {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to rollback a \(typeName(self)) outside its designated queue.")
+        
+        self.context.reset()
+    }
+    
+    
+    // MARK: Internal
+    
+    internal let context: NSManagedObjectContext
+    internal let transactionQueue: GCDQueue
+    internal let childTransactionQueue: GCDQueue = .createSerial("com.corestore.datastack.childtransactionqueue")
+    
+    internal var isCommitted = false
+    internal var result: SaveResult?
+    
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue) {
+        
+        self.transactionQueue = queue
+        
+        let context = mainContext.temporaryContextInTransactionWithConcurrencyType(
+            queue == .Main
+                ? .MainQueueConcurrencyType
+                : .PrivateQueueConcurrencyType
+        )
+        self.context = context
+        
+        context.parentTransaction = self
+    }
+}

CoreStore/Saving and Processing/CoreStore+Transaction.swift

@@ -0,0 +1,65 @@
+//
+//  CoreStore+Transaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - CoreStore
+
+public extension CoreStore {
+    
+    // MARK: Public
+    
+    /**
+    Using the `defaultStack`, begins a transaction asynchronously where `NSManagedObject` creates, updates, and deletes can be made.
+    
+    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent `NSManagedObjectContext`.
+    */
+    public static func beginAsynchronous(closure: (transaction: AsynchronousDataTransaction) -> Void) {
+        
+        self.defaultStack.beginAsynchronous(closure)
+    }
+    
+    /**
+    Using the `defaultStack`, begins a transaction asynchronously where `NSManagedObject` creates, updates, and deletes can be made.
+    
+    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent `NSManagedObjectContext`.
+    :returns: a `SaveResult` value indicating success or failure, or `nil` if the transaction was not comitted synchronously
+    */
+    public static func beginSynchronous(closure: (transaction: SynchronousDataTransaction) -> Void) -> SaveResult? {
+        
+        return self.defaultStack.beginSynchronous(closure)
+    }
+    
+    /**
+    Using the `defaultStack`, begins a non-contiguous transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms. A detached transaction object should typically be only used from the main queue.
+    
+    :returns: a `DetachedDataTransaction` instance where creates, updates, and deletes can be made.
+    */
+    public static func beginDetached() -> DetachedDataTransaction {
+        
+        return self.defaultStack.beginDetached()
+    }
+}

CoreStore/Saving and Processing/DataStack+Transaction.swift

@@ -0,0 +1,81 @@
+//
+//  DataStack+Transaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - DataStack
+
+public extension DataStack {
+    
+    // MARK: Public
+    
+    /**
+    Begins a transaction asynchronously where `NSManagedObject` creates, updates, and deletes can be made.
+    
+    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent `NSManagedObjectContext`.
+    */
+    public func beginAsynchronous(closure: (transaction: AsynchronousDataTransaction) -> Void) {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to begin a transaction from a \(typeName(self)) outside the main thread.")
+        
+        AsynchronousDataTransaction(
+            mainContext: self.rootSavingContext,
+            queue: self.childTransactionQueue,
+            closure: closure).perform()
+    }
+    
+    /**
+    Begins a transaction synchronously where `NSManagedObject` creates, updates, and deletes can be made.
+    
+    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent `NSManagedObjectContext`.
+    :returns: a `SaveResult` value indicating success or failure, or `nil` if the transaction was not comitted synchronously
+    */
+    public func beginSynchronous(closure: (transaction: SynchronousDataTransaction) -> Void) -> SaveResult? {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to begin a transaction from a \(typeName(self)) outside the main thread.")
+        
+        return SynchronousDataTransaction(
+            mainContext: self.rootSavingContext,
+            queue: self.childTransactionQueue,
+            closure: closure).performAndWait()
+    }
+    
+    /**
+    Begins a non-contiguous transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms. A detached transaction object should typically be only used from the main queue.
+    
+    :returns: a `DetachedDataTransaction` instance where creates, updates, and deletes can be made.
+    */
+    public func beginDetached() -> DetachedDataTransaction {
+        
+        CoreStore.assert(NSThread.isMainThread(), "Attempted to begin a transaction from a \(typeName(self)) outside the main thread.")
+        
+        return DetachedDataTransaction(
+            mainContext: self.rootSavingContext,
+            queue: .Main)
+    }
+}

CoreStore/Saving and Processing/DetachedDataTransaction.swift

@@ -0,0 +1,55 @@
+//
+//  DetachedDataTransaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import GCDKit
+
+
+// MARK: - DetachedDataTransaction
+
+/**
+The `DetachedDataTransaction` provides an interface for non-contiguous `NSManagedObject` creates, updates, and deletes. This is useful for making temporary changes, such as partially filled forms. A detached transaction object should typically be only used from the main queue.
+*/
+public final class DetachedDataTransaction: BaseDataTransaction {
+    
+    // MARK: Public
+    
+    /**
+    Saves the transaction changes asynchronously. For a `DetachedDataTransaction`, multiple commits are allowed, although it is the developer's responsibility to ensure a reasonable leeway to prevent blocking the main thread.
+    
+    :param: completion the block executed after the save completes. Success or failure is reported by the `SaveResult` argument of the block.
+    */
+    public func commit(completion: (result: SaveResult) -> Void) {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to commit a \(typeName(self)) outside its designated queue.")
+        
+        self.context.saveAsynchronouslyWithCompletion { (result) -> Void in
+            
+            self.result = result
+            completion(result: result)
+        }
+    }
+}
+

CoreStore/Saving and Processing/SaveResult.swift

@@ -0,0 +1,112 @@
+//
+//  SaveResult.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - SaveResult
+
+/**
+The `SaveResult` indicates the result of a `commit(...)` for a transaction.
+The `SaveResult` can be treated as a boolean:
+
+    CoreStore.beginAsynchronous { transaction in
+        // ...
+        let result = transaction.commit()
+        if result {
+            // succeeded
+        }
+        else {
+            // failed
+        }
+    }
+
+or as an `enum`, where the resulting associated object can also be inspected:
+
+    CoreStore.beginAsynchronous { transaction in
+        // ...
+        let result = transaction.commit()
+        switch result {
+        case .Success(let hasChanges):
+            // hasChanges indicates if there were changes or not
+        case .Failure(let error):
+            // error is the NSError instance for the failure
+        }
+    }
+```
+*/
+public enum SaveResult {
+    
+    // MARK: Public
+    
+    /**
+    `SaveResult.Success` indicates that the `commit()` for the transaction succeeded, either because the save succeeded or because there were no changes to save. The associated value `hasChanges` indicates if there were saved changes or not.
+    */
+    case Success(hasChanges: Bool)
+    
+    /**
+    `SaveResult.Failure` indicates that the `commit()` for the transaction failed. The associated object for this value is the related `NSError` instance.
+    */
+    case Failure(NSError)
+    
+    
+    // MARK: Internal
+    
+    internal init(hasChanges: Bool) {
+        
+        self = .Success(hasChanges: hasChanges)
+    }
+    
+    internal init(_ error: NSError) {
+        
+        self = .Failure(error)
+    }
+    
+    internal init(_ errorCode: CoreStoreErrorCode) {
+        
+        self.init(errorCode, userInfo: nil)
+    }
+    
+    internal init(_ errorCode: CoreStoreErrorCode, userInfo: [NSObject: AnyObject]?) {
+        
+        self.init(NSError(
+            coreStoreErrorCode: errorCode,
+            userInfo: userInfo))
+    }
+}
+
+
+// MARK: - SaveResult: BooleanType
+
+extension SaveResult: BooleanType {
+    
+    public var boolValue: Bool {
+        
+        switch self {
+        case .Success: return true
+        case .Failure: return false
+        }
+    }
+}

CoreStore/Saving and Processing/SynchronousDataTransaction.swift

@@ -0,0 +1,147 @@
+//
+//  SynchronousDataTransaction.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - SynchronousDataTransaction
+
+/**
+The `SynchronousDataTransaction` provides an interface for `NSManagedObject` creates, updates, and deletes. A transaction object should typically be only used from within a transaction block initiated from `DataStack.beginSynchronous(_:)`, or from `CoreStore.beginSynchronous(_:)`.
+*/
+public final class SynchronousDataTransaction: BaseDataTransaction {
+    
+    // MARK: Public
+    
+    /**
+    Saves the transaction changes and waits for completion synchronously. This method should not be used after the `commit()` method was already called once.
+    */
+    public func commit() {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to commit a \(typeName(self)) outside its designated queue.")
+        CoreStore.assert(!self.isCommitted, "Attempted to commit a \(typeName(self)) more than once.")
+        
+        self.isCommitted = true
+        self.result = self.context.saveSynchronously()
+    }
+    
+    /**
+    Begins a child transaction synchronously where `NSManagedObject` creates, updates, and deletes can be made. This method should not be used after the `commit()` method was already called once.
+    
+    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent `NSManagedObjectContext`.
+    :returns: a `SaveResult` value indicating success or failure, or `nil` if the transaction was not comitted synchronously
+    */
+    public func beginSynchronous(closure: (transaction: SynchronousDataTransaction) -> Void) -> SaveResult? {
+        
+        CoreStore.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to begin a child transaction from a \(typeName(self)) outside its designated queue.")
+        CoreStore.assert(!self.isCommitted, "Attempted to begin a child transaction from an already committed \(typeName(self)).")
+        
+        return SynchronousDataTransaction(
+            mainContext: self.context,
+            queue: self.childTransactionQueue,
+            closure: closure).performAndWait()
+    }
+    
+    
+    // MARK: BaseDataTransaction
+    
+    /**
+    Creates a new `NSManagedObject` with the specified entity type.
+    
+    :param: into the `Into` clause indicating the destination `NSManagedObject` entity type and the destination configuration
+    :returns: a new `NSManagedObject` instance of the specified entity type.
+    */
+    public override func create<T: NSManagedObject>(into: Into<T>) -> T {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to create an entity of type <\(T.self)> from an already committed \(typeName(self)).")
+        
+        return super.create(into)
+    }
+    
+    /**
+    Returns an editable proxy of a specified `NSManagedObject`. This method should not be used after the `commit()` method was already called once.
+    
+    :param: object the `NSManagedObject` type to be edited
+    :returns: an editable proxy for the specified `NSManagedObject`.
+    */
+    public override func fetch<T: NSManagedObject>(object: T?) -> T? {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to update an entity of type \(typeName(object)) from an already committed \(typeName(self)).")
+        
+        return super.fetch(object)
+    }
+    
+    /**
+    Deletes a specified `NSManagedObject`. This method should not be used after the `commit()` method was already called once.
+    
+    :param: object the `NSManagedObject` type to be deleted
+    */
+    public override func delete(object: NSManagedObject?) {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to delete an entity of type \(typeName(object)) from an already committed \(typeName(self)).")
+        
+        super.delete(object)
+    }
+    
+    /**
+    Rolls back the transaction by resetting the `NSManagedObjectContext`. After calling this method, all `NSManagedObjects` fetched within the transaction will become invalid. This method should not be used after the `commit()` method was already called once.
+    */
+    public override func rollback() {
+        
+        CoreStore.assert(!self.isCommitted, "Attempted to rollback an already committed \(typeName(self)).")
+        
+        super.rollback()
+    }
+    
+    
+    // MARK: Internal
+    
+    internal func performAndWait() -> SaveResult? {
+        
+        self.transactionQueue.sync {
+            
+            self.closure(transaction: self)
+            if !self.isCommitted && self.hasChanges {
+                
+                CoreStore.log(.Warning, message: "The closure for the \(typeName(self)) completed without being committed. All changes made within the transaction were discarded.")
+            }
+        }
+        return self.result
+    }
+    
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue, closure: (transaction: SynchronousDataTransaction) -> Void) {
+        
+        self.closure = closure
+        
+        super.init(mainContext: mainContext, queue: queue)
+    }
+    
+    
+    // MARK: Private
+    
+    private let closure: (transaction: SynchronousDataTransaction) -> Void
+}

CoreStore/Setting Up/CoreStore+Setup.swift

@@ -0,0 +1,84 @@
+//
+//  CoreStore+Setup.swift
+//  CoreStore
+//
+//  Copyright (c) 2015 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+// MARK: - CoreStore
+
+public extension CoreStore {
+    
+    /**
+    Adds an in-memory store to the `defaultStack`.
+    
+    :param: configuration an optional configuration name from the model file. If not specified, defaults to nil.
+    :returns: a `PersistentStoreResult` indicating success or failure.
+    */
+    public static func addInMemoryStore(configuration: String? = nil) -> PersistentStoreResult {
+        
+        return self.defaultStack.addInMemoryStore(configuration: configuration)
+    }
+    
+    /**
+    Adds to the `defaultStack` an SQLite store from the given SQLite file name.
+    
+    :param: fileName the local filename for the SQLite persistent store in the "Application Support" directory. A new SQLite file will be created if it does not exist.
+    :param: configuration an optional configuration name from the model file. If not specified, defaults to nil.
+    :param: automigrating Set to true to configure Core Data auto-migration, or false to disable. If not specified, defaults to true.
+    :param: resetStoreOnMigrationFailure Set to true to delete the store on migration failure; or set to false to throw exceptions on failure instead. Typically should only be set to true when debugging, or if the persistent store can be recreated easily. If not specified, defaults to false
+    :returns: a `PersistentStoreResult` indicating success or failure.
+    */
+    public static func addSQLiteStore(fileName: String, configuration: String? = nil, automigrating: Bool = true, resetStoreOnMigrationFailure: Bool = false) -> PersistentStoreResult {
+        
+        return self.defaultStack.addSQLiteStore(
+            fileName,
+            configuration: configuration,
+            automigrating: automigrating,
+            resetStoreOnMigrationFailure: resetStoreOnMigrationFailure
+        )
+    }
+    
+    /**
+    Adds to the `defaultStack` an SQLite store from the given SQLite file URL.
+    
+    :param: fileURL the local file URL for the SQLite persistent store. A new SQLite file will be created if it does not exist. If not specified, defaults to a file URL pointing to a "<Application name>.sqlite" file in the "Application Support" directory.
+    :param: configuration an optional configuration name from the model file. If not specified, defaults to nil.
+    :param: automigrating Set to true to configure Core Data auto-migration, or false to disable. If not specified, defaults to true.
+    :param: resetStoreOnMigrationFailure Set to true to delete the store on migration failure; or set to false to throw exceptions on failure instead. Typically should only be set to true when debugging, or if the persistent store can be recreated easily. If not specified, defaults to false.
+    :returns: a `PersistentStoreResult` indicating success or failure.
+    */
+    public static func addSQLiteStore(fileURL: NSURL = defaultSQLiteStoreURL, configuration: String? = nil, automigrating: Bool = true, resetStoreOnMigrationFailure: Bool = false) -> PersistentStoreResult {
+        
+        return self.defaultStack.addSQLiteStore(
+            fileURL: fileURL,
+            configuration: configuration,
+            automigrating: automigrating,
+            resetStoreOnMigrationFailure: resetStoreOnMigrationFailure
+        )
+    }
+    
+}

CoreStore/Setting Up/DataStack.swift

@@ -0,0 +1,363 @@
+//
+//  DataStack.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+import GCDKit
+
+
+private let defaultConfigurationName = "PF_DEFAULT_CONFIGURATION_NAME"
+
+private let applicationSupportDirectory = NSFileManager.defaultManager().URLsForDirectory(.ApplicationSupportDirectory, inDomains: .UserDomainMask).first as! NSURL
+
+private let applicationName = ((NSBundle.mainBundle().objectForInfoDictionaryKey("CFBundleName") as? String) ?? "CoreData")
+
+internal let defaultSQLiteStoreURL = applicationSupportDirectory.URLByAppendingPathComponent(applicationName, isDirectory: false).URLByAppendingPathExtension("sqlite")
+
+
+// MARK: - DataStack
+
+/**
+The `DataStack` encapsulates the data model for the Core Data stack. Each `DataStack` can have multiple data stores, usually specified as a "Configuration" in the model editor. Behind the scenes, the DataStack manages its own `NSPersistentStoreCoordinator`, a root `NSManagedObjectContext` for disk saves, and a shared `NSManagedObjectContext` designed as a read-only model interface for `NSManagedObjects`.
+*/
+public final class DataStack {
+    
+    // MARK: Public
+    
+    /**
+    Initializes a `DataStack` from a model created by merging all the models found in all bundles.
+    */
+    public convenience init() {
+        
+        let mergedModel: NSManagedObjectModel! = NSManagedObjectModel.mergedModelFromBundles(NSBundle.allBundles())
+        CoreStore.assert(mergedModel != nil, "Could not create a merged <\(NSManagedObjectModel.self)> from all bundles.")
+        
+        self.init(managedObjectModel: mergedModel)
+    }
+    
+    /**
+    Initializes a `DataStack` from the specified model name.
+
+    :param: modelName the name of the (.xcdatamodeld) model file.
+    */
+    public convenience init(modelName: String) {
+        
+        let modelFilePath: String! = NSBundle.mainBundle().pathForResource(modelName, ofType: "momd")
+        CoreStore.assert(modelFilePath != nil, "Could not find a \"momd\" resource from the main bundle.")
+        
+        let managedObjectModel: NSManagedObjectModel! = NSManagedObjectModel(contentsOfURL: NSURL(fileURLWithPath: modelFilePath)!)
+        CoreStore.assert(managedObjectModel != nil, "Could not create an <\(NSManagedObjectModel.self)> from the resource at path \"\(modelFilePath)\".")
+        
+        self.init(managedObjectModel: managedObjectModel)
+    }
+    
+    /**
+    Initializes a `DataStack` from an `NSManagedObjectModel`.
+    
+    :param: managedObjectModel the `NSManagedObjectModel` of the (.xcdatamodeld) model file.
+    */
+    public required init(managedObjectModel: NSManagedObjectModel) {
+        
+        self.coordinator = NSPersistentStoreCoordinator(managedObjectModel: managedObjectModel)
+        self.rootSavingContext = NSManagedObjectContext.rootSavingContextForCoordinator(self.coordinator)
+        self.mainContext = NSManagedObjectContext.mainContextForRootContext(self.rootSavingContext)
+        
+        var entityNameMapping = [EntityClassNameType: EntityNameType]()
+        var entityConfigurationsMapping = [EntityClassNameType: Set<String>]()
+        for entityDescription in managedObjectModel.entities as! [NSEntityDescription] {
+            
+            let managedObjectClassName = entityDescription.managedObjectClassName
+            entityConfigurationsMapping[managedObjectClassName] = []
+            if let entityName = entityDescription.name {
+                
+                entityNameMapping[managedObjectClassName] = entityName
+            }
+        }
+        self.entityNameMapping = entityNameMapping
+        self.entityConfigurationsMapping = entityConfigurationsMapping
+        
+        self.rootSavingContext.parentStack = self
+    }
+    
+    /**
+    Adds an in-memory store to the stack.
+    
+    :param: configuration an optional configuration name from the model file. If not specified, defaults to nil.
+    :returns: a `PersistentStoreResult` indicating success or failure.
+    */
+    public func addInMemoryStore(configuration: String? = nil) -> PersistentStoreResult {
+        
+        let coordinator = self.coordinator;
+        var error: NSError?
+        
+        var store: NSPersistentStore?
+        coordinator.performBlockAndWait {
+            
+            store = coordinator.addPersistentStoreWithType(
+                NSInMemoryStoreType,
+                configuration: configuration,
+                URL: nil,
+                options: nil,
+                error: &error)
+        }
+        
+        if let store = store {
+            
+            self.updateMetadataForPersistentStore(store)
+            return PersistentStoreResult(store)
+        }
+        
+        if let error = error {
+            
+            CoreStore.handleError(
+                error,
+                "Failed to add in-memory <\(NSPersistentStore.self)>.")
+            return PersistentStoreResult(error)
+        }
+        else {
+            
+            CoreStore.handleError(
+                NSError(coreStoreErrorCode: .UnknownError),
+                "Failed to add in-memory <\(NSPersistentStore.self)>.")
+            return PersistentStoreResult(.UnknownError)
+        }
+    }
+    
+    /**
+    Adds to the stack an SQLite store from the given SQLite file name.
+    
+    :param: fileName the local filename for the SQLite persistent store in the "Application Support" directory. A new SQLite file will be created if it does not exist. Note that if you have multiple configurations, you will need to specify a different `fileName` explicitly for each of them.
+    :param: configuration an optional configuration name from the model file. If not specified, defaults to `nil`, the "Default" configuration. Note that if you have multiple configurations, you will need to specify a different `fileName` explicitly for each of them.
+    :param: automigrating Set to true to configure Core Data auto-migration, or false to disable. If not specified, defaults to true.
+    :param: resetStoreOnMigrationFailure Set to true to delete the store on migration failure; or set to false to throw exceptions on failure instead. Typically should only be set to true when debugging, or if the persistent store can be recreated easily. If not specified, defaults to false
+    :returns: a `PersistentStoreResult` indicating success or failure.
+    */
+    public func addSQLiteStore(fileName: String, configuration: String? = nil, automigrating: Bool = true, resetStoreOnMigrationFailure: Bool = false) -> PersistentStoreResult {
+        
+        return self.addSQLiteStore(
+            fileURL: applicationSupportDirectory.URLByAppendingPathComponent(
+                fileName,
+                isDirectory: false
+            ),
+            configuration: configuration,
+            automigrating: automigrating,
+            resetStoreOnMigrationFailure: resetStoreOnMigrationFailure
+        )
+    }
+    
+    /**
+    Adds to the stack an SQLite store from the given SQLite file URL.
+    
+    :param: fileURL the local file URL for the SQLite persistent store. A new SQLite file will be created if it does not exist. If not specified, defaults to a file URL pointing to a "<Application name>.sqlite" file in the "Application Support" directory. Note that if you have multiple configurations, you will need to specify a different `fileURL` explicitly for each of them.
+    :param: configuration an optional configuration name from the model file. If not specified, defaults to `nil`, the "Default" configuration. Note that if you have multiple configurations, you will need to specify a different `fileURL` explicitly for each of them.
+    :param: automigrating Set to true to configure Core Data auto-migration, or false to disable. If not specified, defaults to true.
+    :param: resetStoreOnMigrationFailure Set to true to delete the store on migration failure; or set to false to throw exceptions on failure instead. Typically should only be set to true when debugging, or if the persistent store can be recreated easily. If not specified, defaults to false.
+    :returns: a `PersistentStoreResult` indicating success or failure.
+    */
+    public func addSQLiteStore(fileURL: NSURL = defaultSQLiteStoreURL, configuration: String? = nil, automigrating: Bool = true, resetStoreOnMigrationFailure: Bool = false) -> PersistentStoreResult {
+        
+        let coordinator = self.coordinator;
+        if let store = coordinator.persistentStoreForURL(fileURL) {
+            
+            let isExistingStoreAutomigrating = ((store.options?[NSMigratePersistentStoresAutomaticallyOption] as? Bool) ?? false)
+            
+            if store.type == NSSQLiteStoreType
+                && isExistingStoreAutomigrating == automigrating
+                && store.configurationName == (configuration ?? defaultConfigurationName) {
+                    
+                    return PersistentStoreResult(store)
+            }
+            
+            CoreStore.handleError(
+                NSError(coreStoreErrorCode: .DifferentPersistentStoreExistsAtURL),
+                "Failed to add SQLite <\(NSPersistentStore.self)> at \"\(fileURL)\" because a different <\(NSPersistentStore.self)> at that URL already exists.")
+            
+            return PersistentStoreResult(.DifferentPersistentStoreExistsAtURL)
+        }
+        
+        let fileManager = NSFileManager.defaultManager()
+        var directoryError: NSError?
+        if !fileManager.createDirectoryAtURL(
+            fileURL.URLByDeletingLastPathComponent!,
+            withIntermediateDirectories: true,
+            attributes: nil,
+            error: &directoryError) {
+                
+                CoreStore.handleError(
+                    directoryError ?? NSError(coreStoreErrorCode: .UnknownError),
+                    "Failed to create directory for SQLite store at \"\(fileURL)\".")
+                return PersistentStoreResult(directoryError!)
+        }
+        
+        var store: NSPersistentStore?
+        var persistentStoreError: NSError?
+        coordinator.performBlockAndWait {
+            
+            store = coordinator.addPersistentStoreWithType(
+                NSSQLiteStoreType,
+                configuration: configuration,
+                URL: fileURL,
+                options: [NSSQLitePragmasOption: ["WAL": "journal_mode"],
+                    NSInferMappingModelAutomaticallyOption: true,
+                    NSMigratePersistentStoresAutomaticallyOption: automigrating],
+                error: &persistentStoreError)
+        }
+        
+        if let store = store {
+            
+            self.updateMetadataForPersistentStore(store)
+            return PersistentStoreResult(store)
+        }
+        
+        if let error = persistentStoreError
+            where (
+                resetStoreOnMigrationFailure
+                    && (error.code == NSPersistentStoreIncompatibleVersionHashError
+                        || error.code == NSMigrationMissingSourceModelError
+                        || error.code == NSMigrationError)
+                    && error.domain == NSCocoaErrorDomain
+            ) {
+                
+                fileManager.removeItemAtURL(fileURL, error: nil)
+                fileManager.removeItemAtPath(
+                    fileURL.path!.stringByAppendingString("-shm"),
+                    error: nil)
+                fileManager.removeItemAtPath(
+                    fileURL.path!.stringByAppendingString("-wal"),
+                    error: nil)
+                
+                var store: NSPersistentStore?
+                coordinator.performBlockAndWait {
+                    
+                    store = coordinator.addPersistentStoreWithType(
+                        NSSQLiteStoreType,
+                        configuration: configuration,
+                        URL: fileURL,
+                        options: [NSSQLitePragmasOption: ["WAL": "journal_mode"],
+                            NSInferMappingModelAutomaticallyOption: true,
+                            NSMigratePersistentStoresAutomaticallyOption: automigrating],
+                        error: &persistentStoreError)
+                }
+                
+                if let store = store {
+                    
+                    self.updateMetadataForPersistentStore(store)
+                    return PersistentStoreResult(store)
+                }
+        }
+        
+        CoreStore.handleError(
+            persistentStoreError ?? NSError(coreStoreErrorCode: .UnknownError),
+            "Failed to add SQLite <\(NSPersistentStore.self)> at \"\(fileURL)\".")
+        
+        return PersistentStoreResult(.UnknownError)
+    }
+    
+    
+    // MARK: Internal
+    
+    internal let rootSavingContext: NSManagedObjectContext
+    internal let mainContext: NSManagedObjectContext
+    internal let childTransactionQueue: GCDQueue = .createSerial("com.corestore.datastack.childtransactionqueue")
+    
+    internal func entityNameForEntityClass(entityClass: NSManagedObject.Type) -> String? {
+        
+        return self.entityNameMapping[NSStringFromClass(entityClass)]
+    }
+    
+    internal func persistentStoresForEntityClass(entityClass: NSManagedObject.Type) -> [NSPersistentStore]? {
+        
+        var returnValue: [NSPersistentStore]? = nil
+        self.storeMetadataUpdateQueue.barrierSync {
+            
+            let configurationsForEntity = self.entityConfigurationsMapping[NSStringFromClass(entityClass)] ?? []
+            returnValue = map(configurationsForEntity) {
+                
+                return self.configurationStoreMapping[$0]!
+            }
+        }
+        return returnValue
+    }
+    
+    internal func persistentStoreForEntityClass(entityClass: NSManagedObject.Type, configuration: String?, inferStoreIfPossible: Bool) -> (store: NSPersistentStore?, isAmbiguous: Bool) {
+        
+        var returnValue: (store: NSPersistentStore?, isAmbiguous: Bool) = (store: nil, isAmbiguous: false)
+        self.storeMetadataUpdateQueue.barrierSync {
+            
+            let configurationsForEntity = self.entityConfigurationsMapping[NSStringFromClass(entityClass)] ?? []
+            if let configuration = configuration {
+                
+                if configurationsForEntity.contains(configuration) {
+                    
+                    returnValue = (store: self.configurationStoreMapping[configuration], isAmbiguous: false)
+                    return
+                }
+                else if !inferStoreIfPossible {
+                    
+                    return
+                }
+            }
+            
+            switch configurationsForEntity.count {
+                
+            case 0:
+                return
+                
+            case 1 where inferStoreIfPossible:
+                returnValue = (store: self.configurationStoreMapping[configurationsForEntity.first!], isAmbiguous: false)
+                
+            default:
+                returnValue = (store: nil, isAmbiguous: true)
+            }
+        }
+        return returnValue
+    }
+    
+    
+    // MARK: Private
+    
+    private typealias EntityClassNameType = String
+    private typealias EntityNameType = String
+    private typealias ConfigurationNameType = String
+    
+    private let coordinator: NSPersistentStoreCoordinator
+    private let entityNameMapping: [EntityClassNameType: EntityNameType]
+    private let storeMetadataUpdateQueue = GCDQueue.createConcurrent("com.coreStore.persistentStoreBarrierQueue")
+    private var configurationStoreMapping = [ConfigurationNameType: NSPersistentStore]()
+    private var entityConfigurationsMapping = [EntityClassNameType: Set<String>]()
+    
+    private func updateMetadataForPersistentStore(persistentStore: NSPersistentStore) {
+        
+        self.storeMetadataUpdateQueue.barrierAsync {
+            
+            let configurationName = persistentStore.configurationName
+            self.configurationStoreMapping[configurationName] = persistentStore
+            for entityDescription in (self.coordinator.managedObjectModel.entitiesForConfiguration(configurationName) as? [NSEntityDescription] ?? []) {
+                
+                self.entityConfigurationsMapping[entityDescription.managedObjectClassName]?.insert(configurationName)
+            }
+        }
+    }
+}

CoreStore/Setting Up/PersistentStoreResult.swift

@@ -0,0 +1,110 @@
+//
+//  PersistentStoreResult.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+import CoreData
+
+
+// MARK: - PersistentStoreResult
+
+/**
+The `PersistentStoreResult` indicates the result of initializing the persistent store.
+The `PersistentStoreResult` can be treated as a boolean:
+
+    let result = CoreStore.addSQLiteStore()
+    if result {
+    	// succeeded
+    }
+    else {
+    	// failed
+    }
+
+or as an `enum`, where the resulting associated object can also be inspected:
+
+    let result = CoreStore.addSQLiteStore()
+    switch result {
+    case .Success(let persistentStore):
+        // persistentStore is the related NSPersistentStore instance
+    case .Failure(let error):
+        // error is the NSError instance for the failure
+    }
+```
+*/
+public enum PersistentStoreResult {
+    
+    // MARK: Public
+    
+    /**
+    `PersistentStoreResult.Success` indicates that the persistent store process succeeded. The associated object for this `enum` value is the related `NSPersistentStore` instance.
+    */
+    case Success(NSPersistentStore)
+    
+    /**
+    `PersistentStoreResult.Failure` indicates that the persistent store process failed. The associated object for this value is the related `NSError` instance.
+    */
+    case Failure(NSError)
+    
+    
+    // MARK: Internal
+    
+    internal init(_ store: NSPersistentStore) {
+        
+        self = .Success(store)
+    }
+    
+    internal init(_ error: NSError) {
+        
+        self = .Failure(error)
+    }
+    
+    internal init(_ errorCode: CoreStoreErrorCode) {
+        
+        self.init(errorCode, userInfo: nil)
+    }
+    
+    internal init(_ errorCode: CoreStoreErrorCode, userInfo: [NSObject: AnyObject]?) {
+        
+        self.init(NSError(
+            coreStoreErrorCode: errorCode,
+            userInfo: userInfo))
+    }
+}
+
+
+// MARK: - PersistentStoreResult: BooleanType
+
+extension PersistentStoreResult: BooleanType {
+    
+    // MARK: Public
+    
+    public var boolValue: Bool {
+        
+        switch self {
+            
+        case .Success: return true
+        case .Failure: return false
+        }
+    }
+}