added GCDKit to Carthage installation guide

Fix FRCdelegate issue where invalid type is passed

.gitignore

@@ -2,3 +2,5 @@ CoreStoreDemo/CoreStoreDemo.xcodeproj/project.xcworkspace/xcuserdata
 CoreStore.xcodeproj/project.xcworkspace/xcuserdata
 CoreStore.xcodeproj/xcuserdata
 CoreStoreDemo/CoreStoreDemo.xcodeproj/xcuserdata
+Carthage/Build
+CoreStore.xcworkspace/xcuserdata

.gitmodules

@@ -1,3 +1,3 @@
-[submodule "Libraries/GCDKit"]
-	path = Libraries/GCDKit
-	url = git@github.com:JohnEstropia/GCDKit.git
+[submodule "Carthage/Checkouts/GCDKit"]
+	path = Carthage/Checkouts/GCDKit
+	url = https://github.com/JohnEstropia/GCDKit.git

.travis.yml

@@ -0,0 +1,40 @@
+language: objective-c
+osx_image: xcode7.1
+sudo: false
+git:
+  submodules: false
+notifications:
+  email: false
+env:
+  global:
+  - LC_CTYPE=en_US.UTF-8
+  - LANG=en_US.UTF-8
+  matrix:
+    - DESTINATION="OS=9.1,name=iPhone 6s" SCHEME="CoreStore iOS" SDK=iphonesimulator9.1 RUN_TESTS="YES" POD_LINT="NO"
+    - DESTINATION="OS=9.0,name=iPhone 6 Plus" SCHEME="CoreStore iOS" SDK=iphonesimulator9.1 RUN_TESTS="YES" POD_LINT="NO"	
+    - DESTINATION="OS=8.4,name=iPhone 6" SCHEME="CoreStore iOS" SDK=iphonesimulator9.1 RUN_TESTS="YES" POD_LINT="NO"	
+    - DESTINATION="OS=8.3,name=iPhone 5S" SCHEME="CoreStore iOS" SDK=iphonesimulator9.1 RUN_TESTS="YES" POD_LINT="NO"	
+    - DESTINATION="OS=8.2,name=iPhone 5" SCHEME="CoreStore iOS" SDK=iphonesimulator9.1 RUN_TESTS="YES" POD_LINT="NO"
+    - DESTINATION="OS=8.1,name=iPhone 4S" SCHEME="CoreStore iOS" SDK=iphonesimulator9.1 RUN_TESTS="YES" POD_LINT="YES"
+    - DESTINATION="arch=x86_64" SCHEME="CoreStore OSX" SDK=macosx10.11 RUN_TESTS="YES" POD_LINT="NO"
+    - DESTINATION="OS=2.0,name=Apple Watch - 42mm" SCHEME="CoreStore watchOS" SDK=watchsimulator2.0 RUN_TESTS="NO" POD_LINT="NO"
+before_install:
+  - gem install cocoapods --no-rdoc --no-ri --no-document --quiet
+  - gem install xcpretty --no-rdoc --no-ri --no-document --quiet
+  - brew update
+  - brew install carthage
+before_script:
+  - carthage update --use-submodules
+script:
+  - set -o pipefail
+  - xcodebuild -version
+  - xcodebuild -showsdks
+  - if [ $RUN_TESTS == "YES" ]; then 
+      xcodebuild -workspace CoreStore.xcworkspace -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO test | xcpretty -c;
+      xcodebuild -workspace CoreStore.xcworkspace -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO test | xcpretty -c;
+    fi
+  - xcodebuild -workspace "CoreStore.xcworkspace" -scheme "CoreStore iOS" -sdk "iphonesimulator9.1" -destination "OS=9.1,name=iPhone 6s" -configuration Debug ONLY_ACTIVE_ARCH=NO test | xcpretty -c;
+  - xcodebuild -workspace "CoreStore.xcworkspace" -scheme "CoreStore iOS" -sdk "iphonesimulator9.1" -destination "OS=9.1,name=iPhone 6s" -configuration Release ONLY_ACTIVE_ARCH=NO test | xcpretty -c;
+  - if [ $POD_LINT == "YES" ]; then
+      pod lib lint --quick;
+    fi

CartFile

@@ -0,0 +1 @@
+github "JohnEstropia/GCDKit" == 1.1.5

Cartfile.resolved

@@ -0,0 +1 @@
+github "JohnEstropia/GCDKit" "1.1.5"

CoreStore.podspec

@@ -1,16 +1,21 @@
 Pod::Spec.new do |s|
     s.name = "CoreStore"
-    s.version = "1.0.2"
+    s.version = "1.4.0"
     s.license = "MIT"
-    s.summary = "Simple, elegant, and smart Core Data programming with Swift"
+    s.summary = "Unleashing the real power of Core Data with the elegance and safety of Swift"
     s.homepage = "https://github.com/JohnEstropia/CoreStore"
     s.author = { "John Rommel Estropia" => "rommel.estropia@gmail.com" }
     s.source = { :git => "https://github.com/JohnEstropia/CoreStore.git", :tag => s.version.to_s }
 
     s.ios.deployment_target = "8.0"
+    s.osx.deployment_target = "10.10"
+    s.watchos.deployment_target = "2.0"
 
     s.source_files = "CoreStore", "CoreStore/**/*.{swift}"
-    s.frameworks = "Foundation", "UIKit", "CoreData"
+    s.osx.exclude_files = "CoreStore/Observing/*.{swift}", "CoreStore/Internal/FetchedResultsControllerDelegate.swift", "CoreStore/Convenience Helpers/NSFetchedResultsController+Convenience.swift"
+    s.frameworks = "Foundation", "CoreData"
     s.requires_arc = true
-    s.dependency "GCDKit", "1.1.1"
+    s.pod_target_xcconfig = { 'OTHER_SWIFT_FLAGS' => '-D USE_FRAMEWORKS' }
+    
+    s.dependency "GCDKit", "1.1.5"
 end

CoreStore.xcodeproj/xcshareddata/xcschemes/CoreStore OSX.xcscheme

@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "0710"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "B52DD1731BE1F8CC00949AFE"
+               BuildableName = "CoreStore.framework"
+               BlueprintName = "CoreStore OSX"
+               ReferencedContainer = "container:CoreStore.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+         <TestableReference
+            skipped = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "B52DD17C1BE1F8CC00949AFE"
+               BuildableName = "CoreStoreTests.xctest"
+               BlueprintName = "CoreStoreTests OSX"
+               ReferencedContainer = "container:CoreStore.xcodeproj">
+            </BuildableReference>
+         </TestableReference>
+      </Testables>
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "B52DD1731BE1F8CC00949AFE"
+            BuildableName = "CoreStore.framework"
+            BlueprintName = "CoreStore OSX"
+            ReferencedContainer = "container:CoreStore.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+      <AdditionalOptions>
+      </AdditionalOptions>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "B52DD1731BE1F8CC00949AFE"
+            BuildableName = "CoreStore.framework"
+            BlueprintName = "CoreStore OSX"
+            ReferencedContainer = "container:CoreStore.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+      <AdditionalOptions>
+      </AdditionalOptions>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "B52DD1731BE1F8CC00949AFE"
+            BuildableName = "CoreStore.framework"
+            BlueprintName = "CoreStore OSX"
+            ReferencedContainer = "container:CoreStore.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

CoreStore.xcodeproj/xcshareddata/xcschemes/CoreStore iOS.xcscheme

@@ -16,7 +16,7 @@
                BuildableIdentifier = "primary"
                BlueprintIdentifier = "2F03A52F19C5C6DA005002A5"
                BuildableName = "CoreStore.framework"
-               BlueprintName = "CoreStore"
+               BlueprintName = "CoreStore iOS"
                ReferencedContainer = "container:CoreStore.xcodeproj">
             </BuildableReference>
          </BuildActionEntry>
@@ -30,7 +30,7 @@
                BuildableIdentifier = "primary"
                BlueprintIdentifier = "2F03A53A19C5C6DA005002A5"
                BuildableName = "CoreStoreTests.xctest"
-               BlueprintName = "CoreStoreTests"
+               BlueprintName = "CoreStoreTests iOS"
                ReferencedContainer = "container:CoreStore.xcodeproj">
             </BuildableReference>
          </BuildActionEntry>
@@ -48,7 +48,7 @@
                BuildableIdentifier = "primary"
                BlueprintIdentifier = "2F03A53A19C5C6DA005002A5"
                BuildableName = "CoreStoreTests.xctest"
-               BlueprintName = "CoreStoreTests"
+               BlueprintName = "CoreStoreTests iOS"
                ReferencedContainer = "container:CoreStore.xcodeproj">
             </BuildableReference>
          </TestableReference>
@@ -58,7 +58,7 @@
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "2F03A52F19C5C6DA005002A5"
             BuildableName = "CoreStore.framework"
-            BlueprintName = "CoreStore"
+            BlueprintName = "CoreStore iOS"
             ReferencedContainer = "container:CoreStore.xcodeproj">
          </BuildableReference>
       </MacroExpansion>
@@ -80,7 +80,7 @@
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "2F03A52F19C5C6DA005002A5"
             BuildableName = "CoreStore.framework"
-            BlueprintName = "CoreStore"
+            BlueprintName = "CoreStore iOS"
             ReferencedContainer = "container:CoreStore.xcodeproj">
          </BuildableReference>
       </MacroExpansion>
@@ -98,7 +98,7 @@
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "2F03A52F19C5C6DA005002A5"
             BuildableName = "CoreStore.framework"
-            BlueprintName = "CoreStore"
+            BlueprintName = "CoreStore iOS"
             ReferencedContainer = "container:CoreStore.xcodeproj">
          </BuildableReference>
       </MacroExpansion>

CoreStore.xcodeproj/xcshareddata/xcschemes/CoreStore watchOS.xcscheme

@@ -0,0 +1,80 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "0700"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "B563216E1BD65082006C9394"
+               BuildableName = "CoreStore.framework"
+               BlueprintName = "CoreStore watchOS"
+               ReferencedContainer = "container:CoreStore.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+      </Testables>
+      <AdditionalOptions>
+      </AdditionalOptions>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "B563216E1BD65082006C9394"
+            BuildableName = "CoreStore.framework"
+            BlueprintName = "CoreStore watchOS"
+            ReferencedContainer = "container:CoreStore.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+      <AdditionalOptions>
+      </AdditionalOptions>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "B563216E1BD65082006C9394"
+            BuildableName = "CoreStore.framework"
+            BlueprintName = "CoreStore watchOS"
+            ReferencedContainer = "container:CoreStore.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

CoreStore.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "group:CoreStore.xcodeproj">
+   </FileRef>
+   <FileRef
+      location = "group:CoreStoreDemo/CoreStoreDemo.xcodeproj">
+   </FileRef>
+   <FileRef
+      location = "group:Carthage/Checkouts/GCDKit/GCDKit.xcodeproj">
+   </FileRef>
+</Workspace>

CoreStore.xcworkspace/xcshareddata/CoreStore.xcscmblueprint

@@ -0,0 +1,30 @@
+{
+  "DVTSourceControlWorkspaceBlueprintPrimaryRemoteRepositoryKey" : "4B60F1BCB491FF717C56441AE7783C74F417BE48",
+  "DVTSourceControlWorkspaceBlueprintWorkingCopyRepositoryLocationsKey" : {
+
+  },
+  "DVTSourceControlWorkspaceBlueprintWorkingCopyStatesKey" : {
+    "8B2E522D57154DFA93A06982C36315ECBEA4FA97" : 0,
+    "4B60F1BCB491FF717C56441AE7783C74F417BE48" : 0
+  },
+  "DVTSourceControlWorkspaceBlueprintIdentifierKey" : "EBFDEFFE-8BA0-441A-862A-1DE28AA5CD21",
+  "DVTSourceControlWorkspaceBlueprintWorkingCopyPathsKey" : {
+    "8B2E522D57154DFA93A06982C36315ECBEA4FA97" : "CoreStore\/Carthage\/Checkouts\/GCDKit\/",
+    "4B60F1BCB491FF717C56441AE7783C74F417BE48" : "CoreStore\/"
+  },
+  "DVTSourceControlWorkspaceBlueprintNameKey" : "CoreStore",
+  "DVTSourceControlWorkspaceBlueprintVersion" : 204,
+  "DVTSourceControlWorkspaceBlueprintRelativePathToProjectKey" : "CoreStore.xcworkspace",
+  "DVTSourceControlWorkspaceBlueprintRemoteRepositoriesKey" : [
+    {
+      "DVTSourceControlWorkspaceBlueprintRemoteRepositoryURLKey" : "https:\/\/github.com\/JohnEstropia\/CoreStore",
+      "DVTSourceControlWorkspaceBlueprintRemoteRepositorySystemKey" : "com.apple.dt.Xcode.sourcecontrol.Git",
+      "DVTSourceControlWorkspaceBlueprintRemoteRepositoryIdentifierKey" : "4B60F1BCB491FF717C56441AE7783C74F417BE48"
+    },
+    {
+      "DVTSourceControlWorkspaceBlueprintRemoteRepositoryURLKey" : "https:\/\/github.com\/JohnEstropia\/GCDKit.git",
+      "DVTSourceControlWorkspaceBlueprintRemoteRepositorySystemKey" : "com.apple.dt.Xcode.sourcecontrol.Git",
+      "DVTSourceControlWorkspaceBlueprintRemoteRepositoryIdentifierKey" : "8B2E522D57154DFA93A06982C36315ECBEA4FA97"
+    }
+  ]
+}

CoreStore/CartFile

@@ -0,0 +1 @@
+github "JohnEstropia/GCDKit" == 1.1.5

CoreStore/Convenience Helpers/NSFetchedResultsController+Convenience.swift

@@ -0,0 +1,50 @@
+//
+//  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: - NSFetchedResultsController
+
+public extension NSFetchedResultsController {
+    
+    public convenience init<T: NSManagedObject>(dataStack: DataStack, fetchRequest: NSFetchRequest, from: From<T>? = nil, sectionBy: SectionBy? = nil, fetchClauses: [FetchClause]) {
+        
+        let context = dataStack.mainContext
+        from?.applyToFetchRequest(fetchRequest, context: context)
+        for clause in fetchClauses {
+            
+            clause.applyToFetchRequest(fetchRequest)
+        }
+        
+        self.init(
+            fetchRequest: fetchRequest,
+            managedObjectContext: context,
+            sectionNameKeyPath: sectionBy?.sectionKeyPath,
+            cacheName: nil
+        )
+    }
+}

CoreStore/Convenience Helpers/NSManagedObject+Convenience.swift

@@ -37,6 +37,7 @@ public extension NSManagedObject {
     - parameter KVCKey: the KVC key
     - returns: the primitive value for the KVC key
     */
+    @warn_unused_result
     public func accessValueForKVCKey(KVCKey: KeyPath) -> AnyObject? {
         
         self.willAccessValueForKey(KVCKey)
@@ -58,4 +59,20 @@ public extension NSManagedObject {
         self.setPrimitiveValue(value, forKey: KVCKey)
         self.didChangeValueForKey(KVCKey)
     }
+    
+    /**
+    Re-faults the object to use the latest values from the persistent store
+    */
+    public func refreshAsFault() {
+        
+        self.managedObjectContext?.refreshObject(self, mergeChanges: false)
+    }
+    
+    /**
+    Re-faults the object to use the latest values from the persistent store and merges previously pending changes back
+    */
+    public func refreshAndMerge() {
+        
+        self.managedObjectContext?.refreshObject(self, mergeChanges: true)
+    }
 }

CoreStore/Convenience Helpers/NSProgress+Convenience.swift

@@ -24,7 +24,9 @@
 //
 
 import Foundation
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - NSProgress

CoreStore/CoreStore.h

@@ -23,6 +23,7 @@
 //  SOFTWARE.
 //
 
+#import <Foundation/Foundation.h>
 #import <CoreData/CoreData.h>
 
 FOUNDATION_EXPORT double CoreStoreVersionNumber;

CoreStore/CoreStore.swift

@@ -24,7 +24,9 @@
 //
 
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - CoreStore

CoreStore/Fetching and Querying/BaseDataTransaction+Querying.swift

@@ -33,6 +33,68 @@ public extension BaseDataTransaction {
     
     // MARK: Public
     
+    /**
+    Fetches the `NSManagedObject` instance in the transaction's context from a reference created from a transaction or from a different managed object context.
+    
+    - parameter object: a reference to the object created/fetched outside the transaction
+    - returns: the `NSManagedObject` instance if the object exists in the transaction, or `nil` if not found.
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject>(object: T) -> T? {
+        
+        do {
+            
+            return (try self.context.existingObjectWithID(object.objectID) as! T)
+        }
+        catch _ {
+            
+            return nil
+        }
+    }
+    
+    /**
+    Fetches the `NSManagedObject` instance in the transaction's context from an `NSManagedObjectID`.
+    
+    - parameter objectID: the `NSManagedObjectID` for the object
+    - returns: the `NSManagedObject` instance if the object exists in the transaction, or `nil` if not found.
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject>(objectID: NSManagedObjectID) -> T? {
+        
+        do {
+            
+            return (try self.context.existingObjectWithID(objectID) as! T)
+        }
+        catch _ {
+            
+            return nil
+        }
+    }
+    
+    /**
+    Fetches the `NSManagedObject` instances in the transaction's context from references created from a transaction or from a different managed object context.
+    
+    - parameter objects: an array of `NSManagedObject`s created/fetched outside the transaction
+    - returns: the `NSManagedObject` array for objects that exists in the transaction
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject, S: SequenceType where S.Generator.Element == T>(objects: S) -> [T] {
+        
+        return objects.flatMap { (try? self.context.existingObjectWithID($0.objectID)) as? T }
+    }
+    
+    /**
+    Fetches the `NSManagedObject` instances in the transaction's context from a list of `NSManagedObjectID`.
+    
+    - parameter objectIDs: the `NSManagedObjectID` array for the objects
+    - returns: the `NSManagedObject` array for objects that exists in the transaction
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject, S: SequenceType where S.Generator.Element == NSManagedObjectID>(objectIDs: S) -> [T] {
+        
+        return objectIDs.flatMap { (try? self.context.existingObjectWithID($0)) as? T }
+    }
+    
     /**
     Fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     
@@ -40,10 +102,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -57,10 +120,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -74,10 +138,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -91,10 +156,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -108,10 +174,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -125,10 +192,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -142,10 +210,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -159,10 +228,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -176,10 +246,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -193,10 +264,11 @@ public extension BaseDataTransaction {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to fetch from a \(typeName(self)) outside its designated queue."
         )
         
@@ -213,7 +285,7 @@ public extension BaseDataTransaction {
     public func deleteAll<T: NSManagedObject>(from: From<T>, _ deleteClauses: DeleteClause...) -> Int? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to delete from a \(typeName(self)) outside its designated queue."
         )
         
@@ -230,7 +302,7 @@ public extension BaseDataTransaction {
     public func deleteAll<T: NSManagedObject>(from: From<T>, _ deleteClauses: [DeleteClause]) -> Int? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to delete from a \(typeName(self)) outside its designated queue."
         )
         
@@ -247,10 +319,11 @@ public extension BaseDataTransaction {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to query from a \(typeName(self)) outside its designated queue."
         )
         
@@ -267,10 +340,11 @@ public extension BaseDataTransaction {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to query from a \(typeName(self)) outside its designated queue."
         )
         
@@ -287,10 +361,11 @@ public extension BaseDataTransaction {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to query from a \(typeName(self)) outside its designated queue."
         )
         
@@ -307,10 +382,11 @@ public extension BaseDataTransaction {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: [QueryClause]) -> [[NSString: AnyObject]]? {
         
         CoreStore.assert(
-            self.transactionQueue.isCurrentExecutionContext(),
+            self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to query from a \(typeName(self)) outside its designated queue."
         )
         

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

@@ -24,6 +24,7 @@
 //
 
 import Foundation
+import CoreData
 
 
 public func +(left: OrderBy, right: OrderBy) -> OrderBy {

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

@@ -406,11 +406,11 @@ extension Int8: SelectValueResultType {
     
     public static func fromResultObject(result: AnyObject) -> Int8? {
         
-        if let value = (result as? NSNumber)?.longLongValue {
+        guard let value = (result as? NSNumber)?.longLongValue else {
             
-            return numericCast(value) as Int8
+            return nil
         }
-        return nil
+        return numericCast(value) as Int8
     }
 }
 
@@ -426,11 +426,11 @@ extension Int16: SelectValueResultType {
     
     public static func fromResultObject(result: AnyObject) -> Int16? {
         
-        if let value = (result as? NSNumber)?.longLongValue {
+        guard let value = (result as? NSNumber)?.longLongValue else {
             
-            return numericCast(value) as Int16
+            return nil
         }
-        return nil
+        return numericCast(value) as Int16
     }
 }
 
@@ -446,11 +446,11 @@ extension Int32: SelectValueResultType {
     
     public static func fromResultObject(result: AnyObject) -> Int32? {
         
-        if let value = (result as? NSNumber)?.longLongValue {
+        guard let value = (result as? NSNumber)?.longLongValue else {
             
-            return numericCast(value) as Int32
+            return nil
         }
-        return nil
+        return numericCast(value) as Int32
     }
 }
 
@@ -482,11 +482,11 @@ extension Int: SelectValueResultType {
     
     public static func fromResultObject(result: AnyObject) -> Int? {
         
-        if let value = (result as? NSNumber)?.longLongValue {
+        guard let value = (result as? NSNumber)?.longLongValue else {
             
-            return numericCast(value) as Int
+            return nil
         }
-        return nil
+        return numericCast(value) as Int
     }
 }
 

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

@@ -24,6 +24,7 @@
 //
 
 import Foundation
+import CoreData
 
 
 public func &&(left: Where, right: Where) -> Where {
@@ -102,16 +103,38 @@ public struct Where: FetchClause, QueryClause, DeleteClause {
     }
     
     /**
-    Initializes a `Where` clause with a predicate using the specified string format and arguments
+    Initializes a `Where` clause that compares equality
     
-    - parameter format: the format string for the predicate
-    - parameter argumentArray: the arguments for `format`
+    - parameter keyPath: the keyPath to compare with
+    - parameter value: the arguments for the `==` operator
     */
     public init(_ keyPath: KeyPath, isEqualTo value: NSObject?) {
         
         self.init(value == nil
             ? NSPredicate(format: "\(keyPath) == nil")
-            : NSPredicate(format: "\(keyPath) == %@", value!))
+            : NSPredicate(format: "\(keyPath) == %@", argumentArray: [value!]))
+    }
+    
+    /**
+    Initializes a `Where` clause that compares membership
+    
+    - parameter keyPath: the keyPath to compare with
+    - parameter list: the array to check membership of
+    */
+    public init(_ keyPath: KeyPath, isMemberOf list: NSArray) {
+        
+        self.init(NSPredicate(format: "\(keyPath) IN %@", list))
+    }
+    
+    /**
+    Initializes a `Where` clause that compares membership
+    
+    - parameter keyPath: the keyPath to compare with
+    - parameter list: the sequence to check membership of
+    */
+    public init<S: SequenceType where S.Generator.Element: NSObject>(_ keyPath: KeyPath, isMemberOf list: S) {
+        
+        self.init(NSPredicate(format: "\(keyPath) IN %@", Array(list) as NSArray))
     }
     
     public let predicate: NSPredicate

CoreStore/Fetching and Querying/CoreStore+Querying.swift

@@ -24,6 +24,8 @@
 //
 
 import Foundation
+import CoreData
+
 
 // MARK: - CoreStore
 
@@ -31,6 +33,54 @@ public extension CoreStore {
     
     // MARK: Public
     
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObject` instance in the `DataStack`'s context from a reference created from a transaction or from a different managed object context.
+    
+    - parameter object: a reference to the object created/fetched outside the `DataStack`
+    - returns: the `NSManagedObject` instance if the object exists in the `DataStack`, or `nil` if not found.
+    */
+    @warn_unused_result
+    public static func fetchExisting<T: NSManagedObject>(object: T) -> T? {
+        
+        return self.defaultStack.fetchExisting(object)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObject` instance in the `DataStack`'s context from an `NSManagedObjectID`.
+    
+    - parameter objectID: the `NSManagedObjectID` for the object
+    - returns: the `NSManagedObject` instance if the object exists in the `DataStack`, or `nil` if not found.
+    */
+    @warn_unused_result
+    public static func fetchExisting<T: NSManagedObject>(objectID: NSManagedObjectID) -> T? {
+        
+        return self.defaultStack.fetchExisting(objectID)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObject` instances in the `DataStack`'s context from references created from a transaction or from a different managed object context.
+    
+    - parameter objects: an array of `NSManagedObject`s created/fetched outside the `DataStack`
+    - returns: the `NSManagedObject` array for objects that exists in the `DataStack`
+    */
+    @warn_unused_result
+    public static func fetchExisting<T: NSManagedObject, S: SequenceType where S.Generator.Element == T>(objects: S) -> [T] {
+        
+        return self.defaultStack.fetchExisting(objects)
+    }
+    
+    /**
+    Using the `defaultStack`, fetches the `NSManagedObject` instances in the `DataStack`'s context from a list of `NSManagedObjectID`.
+    
+    - parameter objectIDs: the `NSManagedObjectID` array for the objects
+    - returns: the `NSManagedObject` array for objects that exists in the `DataStack`
+    */
+    @warn_unused_result
+    public static func fetchExisting<T: NSManagedObject, S: SequenceType where S.Generator.Element == NSManagedObjectID>(objectIDs: S) -> [T] {
+        
+        return self.defaultStack.fetchExisting(objectIDs)
+    }
+    
     /**
     Using the `defaultStack`, fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     
@@ -38,6 +88,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
         
         return self.defaultStack.fetchOne(from, fetchClauses)
@@ -50,6 +101,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
         
         return self.defaultStack.fetchOne(from, fetchClauses)
@@ -62,6 +114,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
         
         return self.defaultStack.fetchAll(from, fetchClauses)
@@ -74,6 +127,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
         
         return self.defaultStack.fetchAll(from, fetchClauses)
@@ -86,6 +140,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
         
         return self.defaultStack.fetchCount(from, fetchClauses)
@@ -98,6 +153,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
         
         return self.defaultStack.fetchCount(from, fetchClauses)
@@ -110,6 +166,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
         
         return self.defaultStack.fetchObjectID(from, fetchClauses)
@@ -122,6 +179,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
         
         return self.defaultStack.fetchObjectID(from, fetchClauses)
@@ -134,6 +192,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
         
         return self.defaultStack.fetchObjectIDs(from, fetchClauses)
@@ -146,6 +205,7 @@ public extension CoreStore {
     - parameter 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
     */
+    @warn_unused_result
     public static func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
         
         return self.defaultStack.fetchObjectIDs(from, fetchClauses)
@@ -161,6 +221,7 @@ public extension CoreStore {
     - parameter 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.
     */
+    @warn_unused_result
     public static func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
         
         return self.defaultStack.queryValue(from, selectClause, queryClauses)
@@ -176,6 +237,7 @@ public extension CoreStore {
     - parameter 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.
     */
+    @warn_unused_result
     public static func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
         
         return self.defaultStack.queryValue(from, selectClause, queryClauses)
@@ -191,6 +253,7 @@ public extension CoreStore {
     - parameter 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.
     */
+    @warn_unused_result
     public static func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
         
         return self.defaultStack.queryAttributes(from, selectClause, queryClauses)
@@ -206,6 +269,7 @@ public extension CoreStore {
     - parameter 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.
     */
+    @warn_unused_result
     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

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - DataStack
@@ -34,6 +36,68 @@ public extension DataStack {
     
     // MARK: Public
     
+    /**
+    Fetches the `NSManagedObject` instance in the `DataStack`'s context from a reference created from a transaction or from a different managed object context.
+    
+    - parameter object: a reference to the object created/fetched outside the `DataStack`
+    - returns: the `NSManagedObject` instance if the object exists in the `DataStack`, or `nil` if not found.
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject>(object: T) -> T? {
+        
+        do {
+            
+            return (try self.mainContext.existingObjectWithID(object.objectID) as! T)
+        }
+        catch _ {
+            
+            return nil
+        }
+    }
+    
+    /**
+    Fetches the `NSManagedObject` instance in the `DataStack`'s context from an `NSManagedObjectID`.
+    
+    - parameter objectID: the `NSManagedObjectID` for the object
+    - returns: the `NSManagedObject` instance if the object exists in the `DataStack`, or `nil` if not found.
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject>(objectID: NSManagedObjectID) -> T? {
+        
+        do {
+            
+            return (try self.mainContext.existingObjectWithID(objectID) as! T)
+        }
+        catch _ {
+            
+            return nil
+        }
+    }
+    
+    /**
+    Fetches the `NSManagedObject` instances in the `DataStack`'s context from references created from a transaction or from a different managed object context.
+    
+    - parameter objects: an array of `NSManagedObject`s created/fetched outside the `DataStack`
+    - returns: the `NSManagedObject` array for objects that exists in the `DataStack`
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject, S: SequenceType where S.Generator.Element == T>(objects: S) -> [T] {
+        
+        return objects.flatMap { (try? self.mainContext.existingObjectWithID($0.objectID)) as? T }
+    }
+    
+    /**
+    Fetches the `NSManagedObject` instances in the `DataStack`'s context from a list of `NSManagedObjectID`.
+    
+    - parameter objectIDs: the `NSManagedObjectID` array for the objects
+    - returns: the `NSManagedObject` array for objects that exists in the `DataStack`
+    */
+    @warn_unused_result
+    public func fetchExisting<T: NSManagedObject, S: SequenceType where S.Generator.Element == NSManagedObjectID>(objectIDs: S) -> [T] {
+        
+        return objectIDs.flatMap { (try? self.mainContext.existingObjectWithID($0)) as? T }
+    }
+    
     /**
     Fetches the first `NSManagedObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     
@@ -41,6 +105,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
         
         CoreStore.assert(
@@ -58,6 +123,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> T? {
         
         CoreStore.assert(
@@ -75,6 +141,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [T]? {
         
         CoreStore.assert(
@@ -92,6 +159,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchAll<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [T]? {
         
         CoreStore.assert(
@@ -109,6 +177,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> Int? {
         
         CoreStore.assert(
@@ -126,6 +195,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchCount<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> Int? {
         
         CoreStore.assert(
@@ -143,6 +213,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> NSManagedObjectID? {
         
         CoreStore.assert(
@@ -160,6 +231,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectID<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> NSManagedObjectID? {
         
         CoreStore.assert(
@@ -177,6 +249,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> [NSManagedObjectID]? {
         
         CoreStore.assert(
@@ -194,6 +267,7 @@ public extension DataStack {
     - parameter 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
     */
+    @warn_unused_result
     public func fetchObjectIDs<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> [NSManagedObjectID]? {
         
         CoreStore.assert(
@@ -214,6 +288,7 @@ public extension DataStack {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: QueryClause...) -> U? {
         
         CoreStore.assert(
@@ -234,6 +309,7 @@ public extension DataStack {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryValue<T: NSManagedObject, U: SelectValueResultType>(from: From<T>, _ selectClause: Select<U>, _ queryClauses: [QueryClause]) -> U? {
         
         CoreStore.assert(
@@ -254,6 +330,7 @@ public extension DataStack {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: QueryClause...) -> [[NSString: AnyObject]]? {
         
         CoreStore.assert(
@@ -274,6 +351,7 @@ public extension DataStack {
     - parameter 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.
     */
+    @warn_unused_result
     public func queryAttributes<T: NSManagedObject>(from: From<T>, _ selectClause: Select<NSDictionary>, _ queryClauses: [QueryClause]) -> [[NSString: AnyObject]]? {
         
         CoreStore.assert(

CoreStore/Importing Data/BaseDataTransaction+Importing.swift

@@ -0,0 +1,219 @@
+//
+//  BaseDataTransaction+Importing.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: - BaseDataTransaction
+
+public extension BaseDataTransaction {
+    
+    // MARK: Public
+    
+    /**
+    Creates an `ImportableObject` by importing from the specified import source.
+    
+    - parameter into: an `Into` clause specifying the entity type
+    - parameter source: the object to import values from
+    - returns: the created `ImportableObject` instance, or `nil` if the import was ignored
+    */
+    public func importObject<T where T: NSManagedObject, T: ImportableObject>(
+        into: Into<T>,
+        source: T.ImportSource) throws -> T? {
+            
+            CoreStore.assert(
+                self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
+                "Attempted to import an object of type \(typeName(into.entityClass)) outside the transaction's designated queue."
+            )
+            
+            return try autoreleasepool {
+                
+                guard T.shouldInsertFromImportSource(source, inTransaction: self) else {
+                    
+                    return nil
+                }
+                
+                let object = self.create(into)
+                try object.didInsertFromImportSource(source, inTransaction: self)
+                return object
+            }
+    }
+    
+    /**
+    Creates multiple `ImportableObject`s by importing from the specified array of import sources.
+    
+    - parameter into: an `Into` clause specifying the entity type
+    - parameter sourceArray: the array of objects to import values from
+    - returns: the array of created `ImportableObject` instances
+    */
+    public func importObjects<T, S: SequenceType where T: NSManagedObject, T: ImportableObject, S.Generator.Element == T.ImportSource>(
+        into: Into<T>,
+        sourceArray: S) throws -> [T] {
+            
+            CoreStore.assert(
+                self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
+                "Attempted to import an object of type \(typeName(into.entityClass)) outside the transaction's designated queue."
+            )
+            
+            return try autoreleasepool {
+                
+                return try sourceArray.flatMap { (source) -> T? in
+                    
+                    guard T.shouldInsertFromImportSource(source, inTransaction: self) else {
+                        
+                        return nil
+                    }
+                    
+                    return try autoreleasepool {
+                        
+                        let object = self.create(into)
+                        try object.didInsertFromImportSource(source, inTransaction: self)
+                        return object
+                    }
+                }
+            }
+    }
+    
+    /**
+    Updates an existing `ImportableUniqueObject` or creates a new instance by importing from the specified import source.
+    
+    - parameter into: an `Into` clause specifying the entity type
+    - parameter source: the object to import values from
+    - returns: the created/updated `ImportableUniqueObject` instance, or `nil` if the import was ignored
+    */
+    public func importUniqueObject<T where T: NSManagedObject, T: ImportableUniqueObject>(
+        into: Into<T>,
+        source: T.ImportSource) throws -> T?  {
+            
+            CoreStore.assert(
+                self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
+                "Attempted to import an object of type \(typeName(into.entityClass)) outside the transaction's designated queue."
+            )
+            
+            return try autoreleasepool {
+                
+                let uniqueIDKeyPath = T.uniqueIDKeyPath
+                guard let uniqueIDValue = try T.uniqueIDFromImportSource(source, inTransaction: self) else {
+                    
+                    return nil
+                }
+                
+                if let object = self.fetchOne(From(T), Where(uniqueIDKeyPath, isEqualTo: uniqueIDValue)) {
+                    
+                    try object.updateFromImportSource(source, inTransaction: self)
+                    return object
+                }
+                else {
+                    
+                    guard T.shouldInsertFromImportSource(source, inTransaction: self) else {
+                        
+                        return nil
+                    }
+                    
+                    let object = self.create(into)
+                    object.uniqueIDValue = uniqueIDValue
+                    try object.didInsertFromImportSource(source, inTransaction: self)
+                    return object
+                }
+            }
+    }
+    
+    /**
+    Updates existing `ImportableUniqueObject`s or creates them by importing from the specified array of import sources.
+    
+    - parameter into: an `Into` clause specifying the entity type
+    - parameter sourceArray: the array of objects to import values from
+    - parameter preProcess: a closure that lets the caller tweak the internal `UniqueIDType`-to-`ImportSource` mapping to be used for importing. Callers can remove from/add to/update `mapping` and return the updated array from the closure.
+    - returns: the array of created/updated `ImportableUniqueObject` instances
+    */
+    public func importUniqueObjects<T, S: SequenceType where T: NSManagedObject, T: ImportableUniqueObject, S.Generator.Element == T.ImportSource>(
+        into: Into<T>,
+        sourceArray: S,
+        @noescape preProcess: (mapping: [T.UniqueIDType: T.ImportSource]) throws -> [T.UniqueIDType: T.ImportSource] = { $0 }) throws -> [T] {
+            
+            CoreStore.assert(
+                self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
+                "Attempted to import an object of type \(typeName(into.entityClass)) outside the transaction's designated queue."
+            )
+            
+            return try autoreleasepool {
+                
+                var mapping = Dictionary<T.UniqueIDType, T.ImportSource>()
+                let sortedIDs = try autoreleasepool {
+                    
+                    return try sourceArray.flatMap { (source) -> T.UniqueIDType? in
+                        
+                        guard let uniqueIDValue = try T.uniqueIDFromImportSource(source, inTransaction: self) else {
+                            
+                            return nil
+                        }
+                        
+                        mapping[uniqueIDValue] = source
+                        return uniqueIDValue
+                    }
+                }
+                
+                mapping = try autoreleasepool { try preProcess(mapping: mapping) }
+                
+                var objects = Dictionary<T.UniqueIDType, T>()
+                for object in self.fetchAll(From(T), Where(T.uniqueIDKeyPath, isMemberOf: mapping.keys)) ?? [] {
+                    
+                    try autoreleasepool {
+                        
+                        let uniqueIDValue = object.uniqueIDValue
+                        
+                        guard let source = mapping.removeValueForKey(uniqueIDValue)
+                            where T.shouldUpdateFromImportSource(source, inTransaction: self) else {
+                                
+                                return
+                        }
+                        
+                        try object.updateFromImportSource(source, inTransaction: self)
+                        objects[uniqueIDValue] = object
+                    }
+                }
+                
+                for (uniqueIDValue, source) in mapping {
+                    
+                    try autoreleasepool {
+                        
+                        guard T.shouldInsertFromImportSource(source, inTransaction: self) else {
+                            
+                            return
+                        }
+                        
+                        let object = self.create(into)
+                        object.uniqueIDValue = uniqueIDValue
+                        try object.didInsertFromImportSource(source, inTransaction: self)
+                        
+                        objects[uniqueIDValue] = object
+                    }
+                }
+                
+                return sortedIDs.flatMap { objects[$0] }
+            }
+    }
+}

CoreStore/Importing Data/ImportableObject.swift

@@ -0,0 +1,84 @@
+//
+//  ImportableObject.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: - ImportableObject
+
+/**
+`NSManagedObject` subclasses that conform to the `ImportableObject` protocol can be imported from a specified `ImportSource`. This allows transactions to create and insert instances this way:
+
+    class MyPersonEntity: NSManagedObject, ImportableObject {
+        typealias ImportSource = NSDictionary
+        // ...
+    }
+
+    CoreStore.beginAsynchronous { (transaction) -> Void in
+        let json: NSDictionary = // ...
+        let person = try! transaction.importObject(
+            Into(MyPersonEntity),
+            source: json
+        )
+        // ...
+        transaction.commit()
+    }
+*/
+public protocol ImportableObject: class {
+    
+    /**
+    The data type for the import source. This is most commonly an `NSDictionary` or another external source such as an `NSUserDefaults`.
+    */
+    typealias ImportSource
+    
+    /**
+    Return `true` if an object should be created from `source`. Return `false` to ignore and skip `source`. The default implementation returns `true`.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    - returns: `true` if an object should be created from `source`. Return `false` to ignore.
+    */
+    static func shouldInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool
+    
+    /**
+    Implements the actual importing of data from `source`. Implementers should pull values from `source` and assign them to the receiver's attributes. Note that throwing from this method will cause subsequent imports that are part of the same `importObjects(:sourceArray:)` call to be cancelled.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    */
+    func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws
+}
+
+
+// MARK: - ImportableObject (Default Implementations)
+
+public extension ImportableObject {
+    
+    static func shouldInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool {
+        
+        return true
+    }
+}

CoreStore/Importing Data/ImportableUniqueObject.swift

@@ -0,0 +1,136 @@
+//
+//  ImportableUniqueObject.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: - ImportableUniqueObject
+
+/**
+`NSManagedObject` subclasses that conform to the `ImportableUniqueObject` protocol can be imported from a specified `ImportSource`. This allows transactions to either update existing objects or create new instances this way:
+
+    class MyPersonEntity: NSManagedObject, ImportableUniqueObject {
+        typealias ImportSource = NSDictionary
+        typealias UniqueIDType = NSString
+        // ...
+    }
+
+    CoreStore.beginAsynchronous { (transaction) -> Void in
+        let json: NSDictionary = // ...
+        let person = try! transaction.importUniqueObject(
+            Into(MyPersonEntity),
+            source: json
+        )
+        // ...
+        transaction.commit()
+    }
+*/
+public protocol ImportableUniqueObject: ImportableObject {
+    
+    /**
+    The data type for the import source. This is most commonly an `NSDictionary` or another external source such as an `NSUserDefaults`.
+    */
+    typealias ImportSource
+    
+    /**
+    The data type for the entity's unique ID attribute
+    */
+    typealias UniqueIDType: NSObject
+    
+    /**
+    The keyPath to the entity's unique ID attribute
+    */
+    static var uniqueIDKeyPath: String { get }
+    
+    /**
+    The object's unique ID value
+    */
+    var uniqueIDValue: UniqueIDType { get set }
+    
+    /**
+    Return `true` if an object should be created from `source`. Return `false` to ignore and skip `source`. The default implementation returns the value returned by the `shouldUpdateFromImportSource(:inTransaction:)` implementation.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    - returns: `true` if an object should be created from `source`. Return `false` to ignore.
+    */
+    static func shouldInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool
+    
+    /**
+    Return `true` if an object should be updated from `source`. Return `false` to ignore and skip `source`. The default implementation returns `true`.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    - returns: `true` if an object should be updated from `source`. Return `false` to ignore.
+    */
+    static func shouldUpdateFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool
+    
+    /**
+    Return the unique ID as extracted from `source`. This method is called before `shouldInsertFromImportSource(...)` or `shouldUpdateFromImportSource(...)`. Return `nil` to skip importing from `source`. Note that throwing from this method will cause subsequent imports that are part of the same `importUniqueObjects(:sourceArray:)` call to be cancelled.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    - returns: the unique ID as extracted from `source`, or `nil` to skip importing from `source`.
+    */
+    static func uniqueIDFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws -> UniqueIDType?
+    
+    /**
+    Implements the actual importing of data from `source`. This method is called just after the object is created and assigned its unique ID as returned from `uniqueIDFromImportSource(...)`. Implementers should pull values from `source` and assign them to the receiver's attributes. Note that throwing from this method will cause subsequent imports that are part of the same `importUniqueObjects(:sourceArray:)` call to be cancelled. The default implementation simply calls `updateFromImportSource(...)`.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    */
+    func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws
+    
+    /**
+    Implements the actual importing of data from `source`. This method is called just after the existing object is fetched using its unique ID. Implementers should pull values from `source` and assign them to the receiver's attributes. Note that throwing from this method will cause subsequent imports that are part of the same `importUniqueObjects(:sourceArray:)` call to be cancelled.
+    
+    - parameter source: the object to import from
+    - parameter transaction: the transaction that invoked the import. Use the transaction to fetch or create related objects if needed.
+    */
+    func updateFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws
+}
+
+
+// MARK: - ImportableUniqueObject (Default Implementations)
+
+public extension ImportableUniqueObject {
+    
+    static func shouldInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool {
+        
+        return self.shouldUpdateFromImportSource(source, inTransaction: transaction)
+    }
+    
+    static func shouldUpdateFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool {
+        
+        return true
+    }
+    
+    func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws {
+        
+        try self.updateFromImportSource(source, inTransaction: transaction)
+    }
+}

CoreStore/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>1.0.2</string>
+	<string>1.4.0</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>

CoreStore/Internal/FetchedResultsControllerDelegate.swift

@@ -0,0 +1,219 @@
+//
+//  FetchedResultsControllerDelegate.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: - FetchedResultsControllerHandler
+
+@available(OSX, unavailable)
+internal 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
+
+@available(OSX, unavailable)
+internal final class FetchedResultsControllerDelegate: NSObject, NSFetchedResultsControllerDelegate {
+    
+    // MARK: Internal
+    
+    internal var enabled = true
+    
+    internal weak var handler: FetchedResultsControllerHandler?
+    internal weak var fetchedResultsController: NSFetchedResultsController? {
+        
+        didSet {
+            
+            oldValue?.delegate = nil
+            self.fetchedResultsController?.delegate = self
+        }
+    }
+    
+    deinit {
+        
+        self.fetchedResultsController?.delegate = nil
+    }
+    
+    
+    // MARK: NSFetchedResultsControllerDelegate
+    
+    @objc dynamic func controllerWillChangeContent(controller: NSFetchedResultsController) {
+        
+        guard self.enabled else {
+            
+            return
+        }
+        
+        self.deletedSections = []
+        self.insertedSections = []
+        
+        self.handler?.controllerWillChangeContent(controller)
+    }
+    
+    @objc dynamic func controllerDidChangeContent(controller: NSFetchedResultsController) {
+        
+        guard self.enabled else {
+            
+            return
+        }
+        
+        self.handler?.controllerDidChangeContent(controller)
+    }
+    
+    @objc dynamic func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
+        
+        guard self.enabled else {
+            
+            return
+        }
+        
+        guard let actualType = NSFetchedResultsChangeType(rawValue: type.rawValue) else {
+            
+            // This fix is for a bug where iOS passes 0 for NSFetchedResultsChangeType, but this is not a valid enum case.
+            // Swift will then always execute the first case of the switch causing strange behaviour.
+            // https://forums.developer.apple.com/thread/12184#31850
+            return
+        }
+        
+        // This whole dance is a workaround for a nasty bug introduced in XCode 7 targeted at iOS 8 devices
+        // http://stackoverflow.com/questions/31383760/ios-9-attempt-to-delete-and-reload-the-same-index-path/31384014#31384014
+        // https://forums.developer.apple.com/message/9998#9998
+        // https://forums.developer.apple.com/message/31849#31849
+        
+        switch actualType {
+            
+        case .Update:
+            guard let section = indexPath?.indexAtPosition(0) else {
+                
+                return
+            }
+            if self.deletedSections.contains(section)
+                || self.insertedSections.contains(section) {
+                    
+                    return
+            }
+            
+        case .Move:
+            guard let indexPath = indexPath, let newIndexPath = newIndexPath else {
+                
+                return
+            }
+            guard indexPath == newIndexPath else {
+                
+                break
+            }
+            if self.insertedSections.contains(indexPath.indexAtPosition(0)) {
+                
+                // Observers that handle the .Move change are advised to delete then reinsert the object instead of just moving. This is especially true when indexPath and newIndexPath are equal. For example, calling tableView.moveRowAtIndexPath(_:toIndexPath) when both indexPaths are the same will crash the tableView.
+                self.handler?.controller(
+                    controller,
+                    didChangeObject: anObject,
+                    atIndexPath: indexPath,
+                    forChangeType: .Move,
+                    newIndexPath: newIndexPath
+                )
+                return
+            }
+            if self.deletedSections.contains(indexPath.indexAtPosition(0)) {
+                
+                self.handler?.controller(
+                    controller,
+                    didChangeObject: anObject,
+                    atIndexPath: nil,
+                    forChangeType: .Insert,
+                    newIndexPath: indexPath
+                )
+                return
+            }
+            self.handler?.controller(
+                controller,
+                didChangeObject: anObject,
+                atIndexPath: indexPath,
+                forChangeType: .Update,
+                newIndexPath: nil
+            )
+            return
+            
+        default:
+            break
+        }
+        
+        self.handler?.controller(
+            controller,
+            didChangeObject: anObject,
+            atIndexPath: indexPath,
+            forChangeType: actualType,
+            newIndexPath: newIndexPath
+        )
+    }
+    
+    @objc dynamic func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
+        
+        guard self.enabled else {
+            
+            return
+        }
+        
+        switch type {
+            
+        case .Delete:   self.deletedSections.insert(sectionIndex)
+        case .Insert:   self.insertedSections.insert(sectionIndex)
+        default: break
+        }
+        
+        self.handler?.controller(
+            controller,
+            didChangeSection: sectionInfo,
+            atIndex: sectionIndex,
+            forChangeType: type
+        )
+    }
+    
+    @objc dynamic func controller(controller: NSFetchedResultsController, sectionIndexTitleForSectionName sectionName: String) -> String? {
+        
+        return self.handler?.controller(
+            controller,
+            sectionIndexTitleForSectionName: sectionName
+        )
+    }
+    
+    
+    // MARK: Private
+    
+    private var deletedSections = Set<Int>()
+    private var insertedSections = Set<Int>()
+}

CoreStore/Internal/Functions.swift

@@ -0,0 +1,81 @@
+//
+//  Functions.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 autoreleasepool<T>(@noescape closure: () -> T) -> T {
+    
+    var closureValue: T!
+    ObjectiveC.autoreleasepool {
+        
+        closureValue = closure()
+    }
+    
+    return closureValue
+}
+
+internal func autoreleasepool<T>(@noescape closure: () throws -> T) throws -> T {
+    
+    var closureValue: T!
+    var closureError: ErrorType?
+    ObjectiveC.autoreleasepool {
+        
+        do {
+            
+            closureValue = try closure()
+        }
+        catch {
+            
+            closureError = error
+        }
+    }
+    
+    if let closureError = closureError {
+        
+        throw closureError
+    }
+    return closureValue
+}
+
+internal func autoreleasepool(@noescape closure: () throws -> Void) throws {
+    
+    var closureError: ErrorType?
+    ObjectiveC.autoreleasepool {
+        
+        do {
+            
+            try closure()
+        }
+        catch {
+            
+            closureError = error
+        }
+    }
+    
+    if let closureError = closureError {
+        
+        throw closureError
+    }
+}

CoreStore/Internal/MigrationManager.swift

@@ -37,11 +37,12 @@ internal final class MigrationManager: NSMigrationManager, NSProgressReporting {
         
         super.didChangeValueForKey(key)
         
-        if key == "migrationProgress" {
+        guard key == "migrationProgress" else {
             
-            let progress = self.progress
-            progress.completedUnitCount = Int64(Float(progress.totalUnitCount) * self.migrationProgress)
+            return
         }
+        let progress = self.progress
+        progress.completedUnitCount = Int64(Float(progress.totalUnitCount) * self.migrationProgress)
     }
     
     

CoreStore/Internal/NSFileManager+Setup.swift

@@ -17,22 +17,10 @@ internal extension NSFileManager {
     
     internal func removeSQLiteStoreAtURL(fileURL: NSURL) {
         
-        do {
-            
-            try self.removeItemAtURL(fileURL)
-        }
-        catch _ { }
+        _ = try? self.removeItemAtURL(fileURL)
         
-        do {
-            
-            try self.removeItemAtPath(fileURL.path!.stringByAppendingString("-shm"))
-        }
-        catch _ { }
-        
-        do {
-            
-            try self.removeItemAtPath(fileURL.path!.stringByAppendingString("-wal"))
-        }
-        catch _ { }
+        let filePath = fileURL.path!
+        _ = try? self.removeItemAtPath(filePath.stringByAppendingString("-shm"))
+        _ = try? self.removeItemAtPath(filePath.stringByAppendingString("-wal"))
     }
 }

CoreStore/Internal/NSManagedObject+Transaction.swift

@@ -41,82 +41,8 @@ internal extension NSManagedObject {
         )
     }
     
-    internal dynamic class func inContext(context: NSManagedObjectContext, withObjectID objectID: NSManagedObjectID) -> Self? {
-        
-        return self.typedObjectInContext(context, objectID: objectID)
-    }
-    
-    internal func inContext(context: NSManagedObjectContext) -> Self? {
-        
-        return self.typedObjectInContext(context)
-    }
-    
     internal func deleteFromContext() {
         
         self.managedObjectContext?.deleteObject(self)
     }
-    
-    
-    // MARK: Private
-    
-    private class func typedObjectInContext<T: NSManagedObject>(context: NSManagedObjectContext, objectID: NSManagedObjectID) -> T? {
-        
-        do {
-            
-            let existingObject = try context.existingObjectWithID(objectID)
-            return (existingObject as! T)
-        }
-        catch {
-            
-            CoreStore.handleError(
-                error as NSError,
-                "Failed to load existing \(typeName(self)) in context."
-            )
-            return nil
-        }
-    }
-    
-    private func typedObjectInContext<T: NSManagedObject>(context: NSManagedObjectContext) -> T? {
-        
-        let objectID = self.objectID
-        if objectID.temporaryID {
-
-            var objectIDError: NSError?
-            let didSucceed = withExtendedLifetime(self.managedObjectContext) { (context: NSManagedObjectContext?) -> Bool in
-                
-                do {
-                    
-                    try context?.obtainPermanentIDsForObjects([self])
-                    return true
-                }
-                catch {
-                    
-                    objectIDError = error as NSError
-                    return false
-                }
-            }
-            if didSucceed != true {
-                
-                CoreStore.handleError(
-                    objectIDError ?? NSError(coreStoreErrorCode: .UnknownError),
-                    "Failed to obtain permanent ID for object."
-                )
-                return nil
-            }
-        }
-
-        do {
-            
-            let existingObject = try context.existingObjectWithID(objectID)
-            return (existingObject as! T)
-        }
-        catch {
-            
-            CoreStore.handleError(
-                error as NSError,
-                "Failed to load existing \(typeName(self)) in context."
-            )
-            return nil
-        }
-    }
 }

CoreStore/Internal/NSManagedObjectContext+CoreStore.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - NSManagedObjectContext
@@ -61,14 +63,14 @@ internal extension NSManagedObjectContext {
     
     internal func entityDescriptionForEntityClass(entity: AnyClass) -> NSEntityDescription? {
         
-        if let entityName = self.parentStack?.entityNameForEntityClass(entity) {
-
-            return NSEntityDescription.entityForName(
-                entityName,
-                inManagedObjectContext: self
-            )
+        guard let entityName = self.parentStack?.entityNameForEntityClass(entity) else {
+            
+            return nil
         }
-        return nil
+        return NSEntityDescription.entityForName(
+            entityName,
+            inManagedObjectContext: self
+        )
     }
     
     internal func setupForCoreStoreWithContextName(contextName: String) {
@@ -83,7 +85,7 @@ internal extension NSManagedObjectContext {
                 let context = note.object as! NSManagedObjectContext
                 let insertedObjects = context.insertedObjects
                 let numberOfInsertedObjects = insertedObjects.count
-                if numberOfInsertedObjects <= 0 {
+                guard numberOfInsertedObjects > 0 else {
                     
                     return
                 }
@@ -91,7 +93,6 @@ internal extension NSManagedObjectContext {
                 do {
                     
                     try context.obtainPermanentIDsForObjects(Array(insertedObjects))
-                    return
                 }
                 catch {
                     

CoreStore/Internal/NSManagedObjectContext+Querying.swift

@@ -31,7 +31,43 @@ import CoreData
 
 internal extension NSManagedObjectContext {
     
-    // MARK: Public
+    // MARK: Internal
+    
+    internal func fetchExisting<T: NSManagedObject>(object: T) -> T? {
+        
+        if object.objectID.temporaryID {
+            
+            do {
+                
+                try withExtendedLifetime(self) { (context: NSManagedObjectContext) -> Void in
+                    
+                    try context.obtainPermanentIDsForObjects([object])
+                }
+            }
+            catch {
+                
+                CoreStore.handleError(
+                    error as NSError,
+                    "Failed to obtain permanent ID for object."
+                )
+                return nil
+            }
+        }
+        
+        do {
+            
+            let existingObject = try self.existingObjectWithID(object.objectID)
+            return (existingObject as! T)
+        }
+        catch {
+            
+            CoreStore.handleError(
+                error as NSError,
+                "Failed to load existing \(typeName(object)) in context."
+            )
+            return nil
+        }
+    }
     
     internal func fetchOne<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> T? {
         

CoreStore/Internal/NSManagedObjectContext+Setup.swift

@@ -46,7 +46,7 @@ internal extension NSManagedObjectContext {
         }
         set {
             
-            if self.parentContext != nil {
+            guard self.parentContext == nil else {
                 
                 return
             }
@@ -84,6 +84,11 @@ internal extension NSManagedObjectContext {
                 
                 context?.performBlock { () -> Void in
                     
+                    let updatedObjects = (note.userInfo?[NSUpdatedObjectsKey] as? Set<NSManagedObject>) ?? []
+                    for object in updatedObjects {
+                        
+                        context?.objectWithID(object.objectID).willAccessValueForKey(nil)
+                    }
                     context?.mergeChangesFromContextDidSaveNotification(note)
                 }
             }

CoreStore/Internal/NSManagedObjectContext+Transaction.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - NSManagedObjectContext
@@ -71,7 +73,7 @@ internal extension NSManagedObjectContext {
         
         self.performBlockAndWait { [unowned self] () -> Void in
             
-            if !self.hasChanges {
+            guard self.hasChanges else {
                 
                 return
             }
@@ -111,18 +113,15 @@ internal extension NSManagedObjectContext {
         return result
     }
     
-    internal func saveAsynchronouslyWithCompletion(completion: ((result: SaveResult) -> Void)?) {
+    internal func saveAsynchronouslyWithCompletion(completion: ((result: SaveResult) -> Void) = { _ in }) {
         
         self.performBlock { () -> Void in
             
-            if !self.hasChanges {
+            guard self.hasChanges else {
                 
-                if let completion = completion {
+                GCDQueue.Main.async {
                     
-                    GCDQueue.Main.async {
-                        
-                        completion(result: SaveResult(hasChanges: false))
-                    }
+                    completion(result: SaveResult(hasChanges: false))
                 }
                 return
             }
@@ -138,12 +137,9 @@ internal extension NSManagedObjectContext {
                     saveError,
                     "Failed to save \(typeName(NSManagedObjectContext))."
                 )
-                if let completion = completion {
+                GCDQueue.Main.async {
                     
-                    GCDQueue.Main.async {
-                        
-                        completion(result: SaveResult(saveError))
-                    }
+                    completion(result: SaveResult(saveError))
                 }
                 return
             }
@@ -152,7 +148,7 @@ internal extension NSManagedObjectContext {
                 
                 parentContext.saveAsynchronouslyWithCompletion(completion)
             }
-            else if let completion = completion {
+            else {
                 
                 GCDQueue.Main.async {
                     

CoreStore/Internal/NSManagedObjectModel+Setup.swift

@@ -65,10 +65,13 @@ internal extension NSManagedObjectModel {
         }
         else if let resolvedVersion = modelVersions.first ?? modelVersionHints.first {
             
-            CoreStore.log(
-                .Warning,
-                message: "The MigrationChain leaf versions do not include any of the model file's embedded versions. Resolving to version \"\(resolvedVersion)\"."
-            )
+            if !modelVersionHints.isEmpty {
+                
+                CoreStore.log(
+                    .Warning,
+                    message: "The MigrationChain leaf versions do not include any of the model file's embedded versions. Resolving to version \"\(resolvedVersion)\"."
+                )
+            }
             currentModelVersion = resolvedVersion
         }
         else {
@@ -150,6 +153,15 @@ internal extension NSManagedObjectModel {
         return self.entityNameMapping[NSStringFromClass(entityClass)]!
     }
     
+    @nonobjc internal func entityTypesMapping() -> [String: NSManagedObject.Type] {
+    
+        return self.entityNameMapping.reduce([:]) { (var mapping, pair) in
+            
+            mapping[pair.1] = (NSClassFromString(pair.0)! as! NSManagedObject.Type)
+            return mapping
+        }
+    }
+    
     @nonobjc internal func mergedModels() -> [NSManagedObjectModel] {
         
         return self.modelVersions?.map { self[$0] }.flatMap { $0 == nil ? [] : [$0!] } ?? [self]
@@ -183,14 +195,15 @@ internal extension NSManagedObjectModel {
     
     @nonobjc internal subscript(metadata: [String: AnyObject]) -> NSManagedObjectModel? {
         
-        if let modelHashes = metadata[NSStoreModelVersionHashesKey] as? [String : NSData] {
+        guard let modelHashes = metadata[NSStoreModelVersionHashesKey] as? [String : NSData] else {
             
-            for modelVersion in self.modelVersions ?? [] {
+            return nil
+        }
+        for modelVersion in self.modelVersions ?? [] {
+            
+            if let versionModel = self[modelVersion] where modelHashes == versionModel.entityVersionHashesByName {
                 
-                if let versionModel = self[modelVersion] where modelHashes == versionModel.entityVersionHashesByName {
-                    
-                    return versionModel
-                }
+                return versionModel
             }
         }
         return nil

CoreStore/Logging/DefaultLogger.swift

@@ -62,21 +62,26 @@ public final class DefaultLogger: CoreStoreLogger {
                 icon = "❗"
                 levelString = "Fatal"
             }
-            Swift.print("\(icon) [CoreStore: \(levelString)] \(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message)\n")
+            Swift.print("\(icon) [CoreStore: \(levelString)] \((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message)\n")
         #endif
     }
     
     public func handleError(error error: NSError, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString) {
         
         #if DEBUG
-            Swift.print("⚠️ [CoreStore: Error] \(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message)\n    \(error)\n")
+            Swift.print("⚠️ [CoreStore: Error] \((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message)\n    \(error)\n")
         #endif
     }
     
     public func assert(@autoclosure condition: () -> Bool, message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString) {
         
         #if DEBUG
-            Swift.assert(condition, "❗ [CoreStore: Assertion Failure] \(message)", file: fileName, line: numericCast(lineNumber))
+            if condition() {
+                
+                return
+            }
+            Swift.print("❗ [CoreStore: Assertion Failure] \((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ \(message)\n")
+            Swift.fatalError()
         #endif
     }
 }

CoreStore/Migrating/CoreStore+Migration.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - CoreStore
@@ -38,15 +40,17 @@ public extension CoreStore {
     - parameter 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.
     - parameter 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.
     - parameter mappingModelBundles: an optional array of bundles to search mapping model files from. If not set, defaults to the `NSBundle.allBundles()`.
+    - parameter resetStoreOnModelMismatch: Set to true to delete the store on model mismatch; or set to false to report 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.
     - parameter completion: the closure to be executed on the main queue when the process completes, either due to success or failure. The closure's `PersistentStoreResult` argument indicates the result. This closure is NOT executed if an error is thrown, but will be executed with a `.Failure` result if an error occurs asynchronously.
     - returns: an `NSProgress` instance if a migration has started, or `nil` is no migrations are required
     */
-    public static func addSQLiteStore(fileName fileName: String, configuration: String? = nil, mappingModelBundles: [NSBundle]? = nil, completion: (PersistentStoreResult) -> Void) throws -> NSProgress? {
+    public static func addSQLiteStore(fileName fileName: String, configuration: String? = nil, mappingModelBundles: [NSBundle]? = nil, resetStoreOnModelMismatch: Bool = false, completion: (PersistentStoreResult) -> Void) throws -> NSProgress? {
         
         return try self.defaultStack.addSQLiteStore(
             fileName: fileName,
             configuration: configuration,
             mappingModelBundles: mappingModelBundles,
+            resetStoreOnModelMismatch: resetStoreOnModelMismatch,
             completion: completion
         )
     }
@@ -57,15 +61,17 @@ public extension CoreStore {
     - parameter 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.
     - parameter 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.
     - parameter mappingModelBundles: an optional array of bundles to search mapping model files from. If not set, defaults to the `NSBundle.allBundles()`.
+    - parameter resetStoreOnModelMismatch: Set to true to delete the store on model mismatch; or set to false to report 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.
     - parameter completion: the closure to be executed on the main queue when the process completes, either due to success or failure. The closure's `PersistentStoreResult` argument indicates the result. This closure is NOT executed if an error is thrown, but will be executed with a `.Failure` result if an error occurs asynchronously.
     - returns: an `NSProgress` instance if a migration has started, or `nil` is no migrations are required
     */
-    public static func addSQLiteStore(fileURL fileURL: NSURL = defaultSQLiteStoreURL, configuration: String? = nil, mappingModelBundles: [NSBundle]? = NSBundle.allBundles(), completion: (PersistentStoreResult) -> Void) throws -> NSProgress? {
+    public static func addSQLiteStore(fileURL fileURL: NSURL = defaultSQLiteStoreURL, configuration: String? = nil, mappingModelBundles: [NSBundle]? = NSBundle.allBundles(), resetStoreOnModelMismatch: Bool = false, completion: (PersistentStoreResult) -> Void) throws -> NSProgress? {
         
         return try self.defaultStack.addSQLiteStore(
             fileURL: fileURL,
             configuration: configuration,
             mappingModelBundles: mappingModelBundles,
+            resetStoreOnModelMismatch: resetStoreOnModelMismatch,
             completion: completion
         )
     }
@@ -116,6 +122,7 @@ public extension CoreStore {
     - parameter mappingModelBundles: an optional array of bundles to search mapping model files from. If not set, defaults to the `NSBundle.allBundles()`.
     :return: an array of `MigrationType`s indicating the chain of migrations required for the store; or `nil` if either inspection of the store failed, or no mapping model was found/inferred. `MigrationType` acts as a `Bool` and evaluates to `false` if no migration is required, and `true` if either a lightweight or custom migration is needed.
     */
+    @warn_unused_result
     public static func requiredMigrationsForSQLiteStore(fileName fileName: String, configuration: String? = nil, mappingModelBundles: [NSBundle] = NSBundle.allBundles() as [NSBundle]) throws -> [MigrationType] {
         
         return try self.defaultStack.requiredMigrationsForSQLiteStore(
@@ -133,6 +140,7 @@ public extension CoreStore {
     - parameter mappingModelBundles: an optional array of bundles to search mapping model files from. If not set, defaults to the `NSBundle.allBundles()`.
     :return: a `MigrationType` indicating the type of migration required for the store; or `nil` if either inspection of the store failed, or no mapping model was found/inferred. `MigrationType` acts as a `Bool` and evaluates to `false` if no migration is required, and `true` if either a lightweight or custom migration is needed.
     */
+    @warn_unused_result
     public static func requiredMigrationsForSQLiteStore(fileURL fileURL: NSURL = defaultSQLiteStoreURL, configuration: String? = nil, mappingModelBundles: [NSBundle] = NSBundle.allBundles() as [NSBundle]) throws -> [MigrationType] {
         
         return try self.defaultStack.requiredMigrationsForSQLiteStore(

CoreStore/Migrating/DataStack+Migration.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - DataStack
@@ -117,40 +119,37 @@ public extension DataStack {
         let coordinator = self.coordinator;
         if let store = coordinator.persistentStoreForURL(fileURL) {
             
-            if store.type == NSSQLiteStoreType
-                && store.configurationName == (configuration ?? Into.defaultConfigurationName) {
+            guard store.type == NSSQLiteStoreType
+                && store.configurationName == (configuration ?? Into.defaultConfigurationName) else {
                     
-                    GCDQueue.Main.async {
-                        
-                        completion(PersistentStoreResult(store))
-                    }
-                    return nil
+                    let error = NSError(coreStoreErrorCode: .DifferentPersistentStoreExistsAtURL)
+                    CoreStore.handleError(
+                        error,
+                        "Failed to add SQLite \(typeName(NSPersistentStore)) at \"\(fileURL)\" because a different \(typeName(NSPersistentStore)) at that URL already exists."
+                    )
+                    throw error
             }
             
-            let error = NSError(coreStoreErrorCode: .DifferentPersistentStoreExistsAtURL)
-            CoreStore.handleError(
-                error,
-                "Failed to add SQLite \(typeName(NSPersistentStore)) at \"\(fileURL)\" because a different \(typeName(NSPersistentStore)) at that URL already exists."
-            )
-            throw error
+            GCDQueue.Main.async {
+                
+                completion(PersistentStoreResult(store))
+            }
+            return nil
         }
         
         let fileManager = NSFileManager.defaultManager()
-        do {
-            
-            try fileManager.createDirectoryAtURL(
-                fileURL.URLByDeletingLastPathComponent!,
-                withIntermediateDirectories: true,
-                attributes: nil
-            )
-        }
-        catch _ { }
+        _ = try? fileManager.createDirectoryAtURL(
+            fileURL.URLByDeletingLastPathComponent!,
+            withIntermediateDirectories: true,
+            attributes: nil
+        )
         
         do {
             
             let metadata = try NSPersistentStoreCoordinator.metadataForPersistentStoreOfType(
                 NSSQLiteStoreType,
-                URL: fileURL
+                URL: fileURL,
+                options: self.optionsForSQLiteStore()
             )
             
             return self.upgradeSQLiteStoreIfNeeded(
@@ -269,7 +268,8 @@ public extension DataStack {
             
             metadata = try NSPersistentStoreCoordinator.metadataForPersistentStoreOfType(
                 NSSQLiteStoreType,
-                URL: fileURL
+                URL: fileURL,
+                options: self.optionsForSQLiteStore()
             )
         }
         catch {
@@ -298,6 +298,7 @@ public extension DataStack {
     - parameter mappingModelBundles: an optional array of bundles to search mapping model files from. If not set, defaults to the `NSBundle.allBundles()`.
     :return: an array of `MigrationType`s indicating the chain of migrations required for the store; or `nil` if either inspection of the store failed, or no mapping model was found/inferred. `MigrationType` acts as a `Bool` and evaluates to `false` if no migration is required, and `true` if either a lightweight or custom migration is needed.
     */
+    @warn_unused_result
     public func requiredMigrationsForSQLiteStore(fileName fileName: String, configuration: String? = nil, mappingModelBundles: [NSBundle] = NSBundle.allBundles() as [NSBundle]) throws -> [MigrationType] {
         
         return try requiredMigrationsForSQLiteStore(
@@ -318,6 +319,7 @@ public extension DataStack {
     - parameter mappingModelBundles: an optional array of bundles to search mapping model files from. If not set, defaults to the `NSBundle.allBundles()`.
     :return: a `MigrationType` indicating the type of migration required for the store; or `nil` if either inspection of the store failed, or no mapping model was found/inferred. `MigrationType` acts as a `Bool` and evaluates to `false` if no migration is required, and `true` if either a lightweight or custom migration is needed.
     */
+    @warn_unused_result
     public func requiredMigrationsForSQLiteStore(fileURL fileURL: NSURL = defaultSQLiteStoreURL, configuration: String? = nil, mappingModelBundles: [NSBundle] = NSBundle.allBundles() as [NSBundle]) throws -> [MigrationType] {
         
         let metadata: [String : AnyObject]
@@ -325,7 +327,8 @@ public extension DataStack {
             
             metadata = try NSPersistentStoreCoordinator.metadataForPersistentStoreOfType(
                 NSSQLiteStoreType,
-                URL: fileURL
+                URL: fileURL,
+                options: self.optionsForSQLiteStore()
             )
         }
         catch {
@@ -436,7 +439,7 @@ public extension DataStack {
         
         let migrationOperation = NSBlockOperation()
         migrationOperation.qualityOfService = .Utility
-        operations.map { migrationOperation.addDependency($0) }
+        operations.forEach { migrationOperation.addDependency($0) }
         migrationOperation.addExecutionBlock { () -> Void in
             
             GCDQueue.Main.async {

CoreStore/Migrating/MigrationChain.swift

@@ -166,12 +166,10 @@ public struct MigrationChain: NilLiteralConvertible, StringLiteralConvertible, D
         var valid = true
         for version in elements {
             
-            if let lastVersion = lastVersion {
-                
-                if let _ = versionTree.updateValue(version, forKey: lastVersion) {
+            if let lastVersion = lastVersion,
+                let _ = versionTree.updateValue(version, forKey: lastVersion) {
                     
                     valid = false
-                }
             }
             lastVersion = version
         }
@@ -203,11 +201,11 @@ public struct MigrationChain: NilLiteralConvertible, StringLiteralConvertible, D
     
     internal func nextVersionFrom(version: String) -> String? {
         
-        if let nextVersion = self.versionTree[version] where nextVersion != version {
+        guard let nextVersion = self.versionTree[version] where nextVersion != version else {
             
-            return nextVersion
+            return nil
         }
-        return nil
+        return nextVersion
     }
     
     
@@ -237,9 +235,9 @@ extension MigrationChain: CustomDebugStringConvertible {
                 steps.append(nextVersion)
                 version = nextVersion
             }
-            paths.append(" → ".join(steps))
+            paths.append(steps.joinWithSeparator(" → "))
         }
         
-        return "[" + "], [".join(paths) + "]"
+        return "[" + paths.joinWithSeparator("], [") + "]"
     }
 }

CoreStore/NSError+CoreStore.swift

@@ -24,6 +24,7 @@
 //
 
 import Foundation
+import CoreData
 
 /**
 The `NSError` error domain for `CoreStore`.

CoreStore/Observing/CoreStore+Observing.swift

@@ -29,6 +29,7 @@ import CoreData
 
 // MARK: - CoreStore
 
+@available(OSX, unavailable)
 public extension CoreStore {
     
     // MARK: Public
@@ -39,6 +40,7 @@ public extension CoreStore {
     - parameter object: the `NSManagedObject` to observe changes from
     - returns: a `ObjectMonitor` that monitors changes to `object`
     */
+    @warn_unused_result
     public static func monitorObject<T: NSManagedObject>(object: T) -> ObjectMonitor<T> {
         
         return self.defaultStack.monitorObject(object)
@@ -50,8 +52,9 @@ public extension CoreStore {
     - parameter from: a `From` clause indicating the entity type
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
-    */
-    public static func monitorList<T: NSManagedObject>(from: From<T>, _ groupBy: GroupBy? = nil, _ queryClauses: FetchClause...) -> ListMonitor<T> {
+     */
+    @warn_unused_result
+    public static func monitorList<T: NSManagedObject>(from: From<T>, _ queryClauses: FetchClause...) -> ListMonitor<T> {
         
         return self.defaultStack.monitorList(from, queryClauses)
     }
@@ -63,11 +66,36 @@ public extension CoreStore {
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
     */
-    public static func monitorList<T: NSManagedObject>(from: From<T>, _ groupBy: GroupBy? = nil, _ queryClauses: [FetchClause]) -> ListMonitor<T> {
+    @warn_unused_result
+    public static func monitorList<T: NSManagedObject>(from: From<T>, _ queryClauses: [FetchClause]) -> ListMonitor<T> {
         
         return self.defaultStack.monitorList(from, queryClauses)
     }
     
+    /**
+     Using the `defaultStack`, asynchronously creates a `ListMonitor` for a list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public static func monitorList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ fetchClauses: FetchClause...) {
+        
+        self.defaultStack.monitorList(createAsynchronously: createAsynchronously, from, fetchClauses)
+    }
+    
+    /**
+     Using the `defaultStack`, asynchronously creates a `ListMonitor` for a list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public static func monitorList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ fetchClauses: [FetchClause])  {
+        
+        self.defaultStack.monitorList(createAsynchronously: createAsynchronously, from, fetchClauses)
+    }
+    
     /**
     Using the `defaultStack`, creates a `ListMonitor` for a sectioned list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list.
     
@@ -76,6 +104,7 @@ public extension CoreStore {
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
     */
+    @warn_unused_result
     public static func monitorSectionedList<T: NSManagedObject>(from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: FetchClause...) -> ListMonitor<T> {
         
         return self.defaultStack.monitorSectionedList(from, sectionBy, fetchClauses)
@@ -89,8 +118,35 @@ public extension CoreStore {
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
     */
+    @warn_unused_result
     public static func monitorSectionedList<T: NSManagedObject>(from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: [FetchClause]) -> ListMonitor<T> {
         
         return self.defaultStack.monitorSectionedList(from, sectionBy, fetchClauses)
     }
+    
+    /**
+     Using the `defaultStack`, asynchronously creates a `ListMonitor` for a sectioned list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter sectionBy: a `SectionBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public static func monitorSectionedList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: FetchClause...) {
+        
+        self.defaultStack.monitorSectionedList(createAsynchronously: createAsynchronously, from, sectionBy, fetchClauses)
+    }
+    
+    /**
+     Using the `defaultStack`, asynchronously creates a `ListMonitor` for a sectioned list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter sectionBy: a `SectionBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public static func monitorSectionedList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: [FetchClause]) {
+        
+        self.defaultStack.monitorSectionedList(createAsynchronously: createAsynchronously, from, sectionBy, fetchClauses)
+    }
 }

CoreStore/Observing/DataStack+Observing.swift

@@ -25,11 +25,14 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - DataStack
 
+@available(OSX, unavailable)
 public extension DataStack {
     
     // MARK: Public
@@ -40,6 +43,7 @@ public extension DataStack {
     - parameter object: the `NSManagedObject` to observe changes from
     - returns: a `ObjectMonitor` that monitors changes to `object`
     */
+    @warn_unused_result
     public func monitorObject<T: NSManagedObject>(object: T) -> ObjectMonitor<T> {
         
         CoreStore.assert(
@@ -59,7 +63,8 @@ public extension DataStack {
     - parameter from: a `From` clause indicating the entity type
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
-    */
+     */
+    @warn_unused_result
     public func monitorList<T: NSManagedObject>(from: From<T>, _ fetchClauses: FetchClause...) -> ListMonitor<T> {
         
         return self.monitorList(from, fetchClauses)
@@ -71,7 +76,8 @@ public extension DataStack {
     - parameter from: a `From` clause indicating the entity type
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
-    */
+     */
+    @warn_unused_result
     public func monitorList<T: NSManagedObject>(from: From<T>, _ fetchClauses: [FetchClause]) -> ListMonitor<T> {
         
         CoreStore.assert(
@@ -91,6 +97,45 @@ public extension DataStack {
         )
     }
     
+    /**
+     Asynchronously creates a `ListMonitor` for a list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public func monitorList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ fetchClauses: FetchClause...) {
+        
+        self.monitorList(createAsynchronously: createAsynchronously, from, fetchClauses)
+    }
+    
+    /**
+     Asynchronously creates a `ListMonitor` for a list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public func monitorList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ fetchClauses: [FetchClause])  {
+        
+        CoreStore.assert(
+            NSThread.isMainThread(),
+            "Attempted to observe objects from \(typeName(self)) outside the main thread."
+        )
+        CoreStore.assert(
+            fetchClauses.filter { $0 is OrderBy }.count > 0,
+            "A ListMonitor requires an OrderBy clause."
+        )
+        
+        _ = ListMonitor(
+            dataStack: self,
+            from: from,
+            sectionBy: nil,
+            fetchClauses: fetchClauses,
+            createAsynchronously: createAsynchronously
+        )
+    }
+    
     /**
     Creates a `ListMonitor` for a sectioned list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list.
     
@@ -98,7 +143,8 @@ public extension DataStack {
     - parameter sectionBy: a `SectionBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
-    */
+     */
+    @warn_unused_result
     public func monitorSectionedList<T: NSManagedObject>(from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: FetchClause...) -> ListMonitor<T> {
      
         return self.monitorSectionedList(from, sectionBy, fetchClauses)
@@ -111,7 +157,8 @@ public extension DataStack {
     - parameter sectionBy: a `SectionBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
     - returns: a `ListMonitor` instance that monitors changes to the list
-    */
+     */
+    @warn_unused_result
     public func monitorSectionedList<T: NSManagedObject>(from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: [FetchClause]) -> ListMonitor<T> {
         
         CoreStore.assert(
@@ -130,4 +177,45 @@ public extension DataStack {
             fetchClauses: fetchClauses
         )
     }
+    
+    /**
+     Asynchronously creates a `ListMonitor` for a sectioned list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter sectionBy: a `SectionBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public func monitorSectionedList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: FetchClause...) {
+        
+        self.monitorSectionedList(createAsynchronously: createAsynchronously, from, sectionBy, fetchClauses)
+    }
+    
+    /**
+     Asynchronously creates a `ListMonitor` for a sectioned list of `NSManagedObject`s that satisfy the specified fetch clauses. Multiple `ListObserver`s may then register themselves to be notified when changes are made to the list. Since `NSFetchedResultsController` greedily locks the persistent store on initial fetch, you may prefer this method instead of the synchronous counterpart to avoid deadlocks while background updates/saves are being executed.
+     
+     - parameter createAsynchronously: the closure that receives the created `ListMonitor` instance
+     - parameter from: a `From` clause indicating the entity type
+     - parameter sectionBy: a `SectionBy` clause indicating the keyPath for the attribute to use when sorting the list into sections.
+     - parameter fetchClauses: a series of `FetchClause` instances for fetching the object list. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
+     */
+    public func monitorSectionedList<T: NSManagedObject>(createAsynchronously createAsynchronously: (ListMonitor<T>) -> Void, _ from: From<T>, _ sectionBy: SectionBy, _ fetchClauses: [FetchClause]) {
+        
+        CoreStore.assert(
+            NSThread.isMainThread(),
+            "Attempted to observe objects from \(typeName(self)) outside the main thread."
+        )
+        CoreStore.assert(
+            fetchClauses.filter { $0 is OrderBy }.count > 0,
+            "A ListMonitor requires an OrderBy clause."
+        )
+        
+        _ = ListMonitor(
+            dataStack: self,
+            from: from,
+            sectionBy: sectionBy,
+            fetchClauses: fetchClauses,
+            createAsynchronously: createAsynchronously
+        )
+    }
 }

CoreStore/Observing/ListObserver.swift

@@ -38,26 +38,68 @@ Implement the `ListObserver` protocol to observe changes to a list of `NSManaged
     )
     monitor.addObserver(self)
 */
+@available(OSX, unavailable)
 public protocol ListObserver: class {
     
     /**
     The `NSManagedObject` type for the observed list
     */
-    typealias EntityType: NSManagedObject
+    typealias ListEntityType: NSManagedObject
     
     /**
     Handles processing just before a change to the observed list occurs
     
     - parameter monitor: the `ListMonitor` monitoring the list being observed
     */
-    func listMonitorWillChange(monitor: ListMonitor<EntityType>)
+    func listMonitorWillChange(monitor: ListMonitor<ListEntityType>)
     
     /**
     Handles processing right after a change to the observed list occurs
     
     - parameter monitor: the `ListMonitor` monitoring the object being observed
     */
-    func listMonitorDidChange(monitor: ListMonitor<EntityType>)
+    func listMonitorDidChange(monitor: ListMonitor<ListEntityType>)
+    
+    /**
+    This method is broadcast from within the `ListMonitor`'s `refetch(...)` method to let observers prepare for the internal `NSFetchedResultsController`'s pending change to its predicate, sort descriptors, etc. Note that the actual refetch will happen after the `NSFetchedResultsController`'s last `controllerDidChangeContent(_:)` notification completes.
+    
+    - parameter monitor: the `ListMonitor` monitoring the object being observed
+    */
+    func listMonitorWillRefetch(monitor: ListMonitor<ListEntityType>)
+    
+    /**
+    After the `ListMonitor`'s `refetch(...)` method is called, this method is broadcast after the `NSFetchedResultsController`'s last `controllerDidChangeContent(_:)` notification completes.
+    
+    - parameter monitor: the `ListMonitor` monitoring the object being observed
+    */
+    func listMonitorDidRefetch(monitor: ListMonitor<ListEntityType>)
+}
+
+
+// MARK: - ListObserver (Default Implementations)
+
+@available(OSX, unavailable)
+public extension ListObserver {
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitorWillChange(monitor: ListMonitor<ListEntityType>) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitorDidChange(monitor: ListMonitor<ListEntityType>) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitorWillRefetch(monitor: ListMonitor<ListEntityType>) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitorDidRefetch(monitor: ListMonitor<ListEntityType>) { }
 }
 
 
@@ -72,6 +114,7 @@ Implement the `ListObjectObserver` protocol to observe detailed changes to a lis
     )
     monitor.addObserver(self)
 */
+@available(OSX, unavailable)
 public protocol ListObjectObserver: ListObserver {
     
     /**
@@ -81,7 +124,7 @@ public protocol ListObjectObserver: ListObserver {
     - parameter object: the entity type for the inserted object
     - parameter indexPath: the new `NSIndexPath` for the inserted object
     */
-    func listMonitor(monitor: ListMonitor<EntityType>, didInsertObject object: EntityType, toIndexPath indexPath: NSIndexPath)
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didInsertObject object: ListEntityType, toIndexPath indexPath: NSIndexPath)
     
     /**
     Notifies that an object was deleted from the specified `NSIndexPath` in the list
@@ -90,7 +133,7 @@ public protocol ListObjectObserver: ListObserver {
     - parameter object: the entity type for the deleted object
     - parameter indexPath: the `NSIndexPath` for the deleted object
     */
-    func listMonitor(monitor: ListMonitor<EntityType>, didDeleteObject object: EntityType, fromIndexPath indexPath: NSIndexPath)
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didDeleteObject object: ListEntityType, fromIndexPath indexPath: NSIndexPath)
     
     /**
     Notifies that an object at the specified `NSIndexPath` was updated
@@ -99,7 +142,7 @@ public protocol ListObjectObserver: ListObserver {
     - parameter object: the entity type for the updated object
     - parameter indexPath: the `NSIndexPath` for the updated object
     */
-    func listMonitor(monitor: ListMonitor<EntityType>, didUpdateObject object: EntityType, atIndexPath indexPath: NSIndexPath)
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didUpdateObject object: ListEntityType, atIndexPath indexPath: NSIndexPath)
     
     /**
     Notifies that an object's index changed
@@ -109,7 +152,34 @@ public protocol ListObjectObserver: ListObserver {
     - parameter fromIndexPath: the previous `NSIndexPath` for the moved object
     - parameter toIndexPath: the new `NSIndexPath` for the moved object
     */
-    func listMonitor(monitor: ListMonitor<EntityType>, didMoveObject object: EntityType, fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath)
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didMoveObject object: ListEntityType, fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath)
+}
+
+
+// MARK: - ListObjectObserver (Default Implementations)
+
+@available(OSX, unavailable)
+public extension ListObjectObserver {
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didInsertObject object: ListEntityType, toIndexPath indexPath: NSIndexPath) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didDeleteObject object: ListEntityType, fromIndexPath indexPath: NSIndexPath) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didUpdateObject object: ListEntityType, atIndexPath indexPath: NSIndexPath) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didMoveObject object: ListEntityType, fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath) { }
 }
 
 
@@ -125,6 +195,7 @@ Implement the `ListSectionObserver` protocol to observe changes to a list's sect
     )
     monitor.addObserver(self)
 */
+@available(OSX, unavailable)
 public protocol ListSectionObserver: ListObjectObserver {
     
     /**
@@ -133,8 +204,8 @@ public protocol ListSectionObserver: ListObjectObserver {
     - parameter monitor: the `ListMonitor` monitoring the list being observed
     - parameter sectionInfo: the `NSFetchedResultsSectionInfo` for the inserted section
     - parameter sectionIndex: the new section index for the new section
-    */
-    func listMonitor(monitor: ListMonitor<EntityType>, didInsertSection sectionInfo: NSFetchedResultsSectionInfo, toSectionIndex sectionIndex: Int)
+     */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didInsertSection sectionInfo: NSFetchedResultsSectionInfo, toSectionIndex sectionIndex: Int)
     
     /**
     Notifies that a section was inserted at the specified index
@@ -142,6 +213,23 @@ public protocol ListSectionObserver: ListObjectObserver {
     - parameter monitor: the `ListMonitor` monitoring the list being observed
     - parameter sectionInfo: the `NSFetchedResultsSectionInfo` for the deleted section
     - parameter sectionIndex: the previous section index for the deleted section
-    */
-    func listMonitor(monitor: ListMonitor<EntityType>, didDeleteSection sectionInfo: NSFetchedResultsSectionInfo, fromSectionIndex sectionIndex: Int)
+     */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didDeleteSection sectionInfo: NSFetchedResultsSectionInfo, fromSectionIndex sectionIndex: Int)
+}
+
+
+// MARK: - ListSectionObserver (Default Implementations)
+
+@available(OSX, unavailable)
+public extension ListSectionObserver {
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didInsertSection sectionInfo: NSFetchedResultsSectionInfo, toSectionIndex sectionIndex: Int) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func listMonitor(monitor: ListMonitor<ListEntityType>, didDeleteSection sectionInfo: NSFetchedResultsSectionInfo, fromSectionIndex sectionIndex: Int) { }
 }

CoreStore/Observing/ObjectMonitor.swift

@@ -25,21 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
-
-
-private let ObjectMonitorWillChangeObjectNotification = "ObjectMonitorWillChangeObjectNotification"
-private let ObjectMonitorDidDeleteObjectNotification = "ObjectMonitorDidDeleteObjectNotification"
-private let ObjectMonitorDidUpdateObjectNotification = "ObjectMonitorDidUpdateObjectNotification"
-
-private let UserInfoKeyObject = "UserInfoKeyObject"
-
-private struct NotificationKey {
-    
-    static var willChangeObject: Void?
-    static var didDeleteObject: Void?
-    static var didUpdateObject: Void?
-}
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - ObjectMonitor
@@ -54,6 +42,7 @@ The created `ObjectMonitor` instance needs to be held on (retained) for as long
 
 Observers registered via `addObserver(_:)` are not retained. `ObjectMonitor` only keeps a `weak` reference to all observers, thus keeping itself free from retain-cycles.
 */
+@available(OSX, unavailable)
 public final class ObjectMonitor<T: NSManagedObject> {
     
     // MARK: Public
@@ -85,7 +74,7 @@ public final class ObjectMonitor<T: NSManagedObject> {
     
     - parameter observer: an `ObjectObserver` to send change notifications to
     */
-    public func addObserver<U: ObjectObserver where U.EntityType == T>(observer: U) {
+    public func addObserver<U: ObjectObserver where U.ObjectEntityType == T>(observer: U) {
         
         CoreStore.assert(
             NSThread.isMainThread(),
@@ -95,56 +84,60 @@ public final class ObjectMonitor<T: NSManagedObject> {
         self.removeObserver(observer)
         
         self.registerChangeNotification(
-            &NotificationKey.willChangeObject,
+            &self.willChangeObjectKey,
             name: ObjectMonitorWillChangeObjectNotification,
             toObserver: observer,
             callback: { [weak observer] (monitor) -> Void in
                 
-                if let object = monitor.object, let observer = observer {
+                guard let object = monitor.object, let observer = observer else {
                     
-                    observer.objectMonitor(monitor, willUpdateObject: object)
+                    return
                 }
+                observer.objectMonitor(monitor, willUpdateObject: object)
             }
         )
         self.registerObjectNotification(
-            &NotificationKey.didDeleteObject,
+            &self.didDeleteObjectKey,
             name: ObjectMonitorDidDeleteObjectNotification,
             toObserver: observer,
             callback: { [weak observer] (monitor, object) -> Void in
                 
-                if let observer = observer {
+                guard let observer = observer else {
                     
-                    observer.objectMonitor(monitor, didDeleteObject: object)
+                    return
                 }
+                observer.objectMonitor(monitor, didDeleteObject: object)
             }
         )
         self.registerObjectNotification(
-            &NotificationKey.didUpdateObject,
+            &self.didUpdateObjectKey,
             name: ObjectMonitorDidUpdateObjectNotification,
             toObserver: observer,
             callback: { [weak self, weak observer] (monitor, object) -> Void in
                 
-                if let strongSelf = self, let observer = observer {
+                guard let strongSelf = self, let observer = observer else {
                     
-                    let previousCommitedAttributes = strongSelf.lastCommittedAttributes
-                    let currentCommitedAttributes = object.committedValuesForKeys(nil) as! [String: NSObject]
-                    
-                    let changedKeys = currentCommitedAttributes.keys.reduce(Set<String>()) { (var changedKeys, key) -> Set<String> in
-                        
-                        if previousCommitedAttributes[key] != currentCommitedAttributes[key] {
-                            
-                            changedKeys.insert(key)
-                        }
-                        return changedKeys
-                    }
-                    
-                    strongSelf.lastCommittedAttributes = currentCommitedAttributes
-                    observer.objectMonitor(
-                        monitor,
-                        didUpdateObject: object,
-                        changedPersistentKeys: changedKeys
-                    )
+                    return
                 }
+                
+                let previousCommitedAttributes = strongSelf.lastCommittedAttributes
+                let currentCommitedAttributes = object.committedValuesForKeys(nil) as! [String: NSObject]
+                
+                var changedKeys = Set<String>()
+                for key in currentCommitedAttributes.keys {
+                    
+                    if previousCommitedAttributes[key] != currentCommitedAttributes[key] {
+                        
+                        changedKeys.insert(key)
+                    }
+                }
+                
+                strongSelf.lastCommittedAttributes = currentCommitedAttributes
+                observer.objectMonitor(
+                    monitor,
+                    didUpdateObject: object,
+                    changedPersistentKeys: changedKeys
+                )
             }
         )
     }
@@ -156,7 +149,7 @@ public final class ObjectMonitor<T: NSManagedObject> {
     
     - parameter observer: an `ObjectObserver` to unregister notifications to
     */
-    public func removeObserver<U: ObjectObserver where U.EntityType == T>(observer: U) {
+    public func removeObserver<U: ObjectObserver where U.ObjectEntityType == T>(observer: U) {
         
         CoreStore.assert(
             NSThread.isMainThread(),
@@ -164,9 +157,9 @@ public final class ObjectMonitor<T: NSManagedObject> {
         )
         
         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)
+        setAssociatedRetainedObject(nilValue, forKey: &self.willChangeObjectKey, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &self.didDeleteObjectKey, inObject: observer)
+        setAssociatedRetainedObject(nilValue, forKey: &self.didUpdateObjectKey, inObject: observer)
     }
     
     
@@ -174,28 +167,22 @@ public final class ObjectMonitor<T: NSManagedObject> {
     
     internal init(dataStack: DataStack, object: T) {
         
-        let context = dataStack.mainContext
-        
         let fetchRequest = NSFetchRequest()
         fetchRequest.entity = object.entity
-        
-        fetchRequest.fetchLimit = 1
+        fetchRequest.fetchLimit = 0
         fetchRequest.resultType = .ManagedObjectResultType
         fetchRequest.sortDescriptors = []
-        
-        let originalObjectID = object.objectID
-        Where("SELF", isEqualTo: originalObjectID).applyToFetchRequest(fetchRequest)
+        fetchRequest.includesPendingChanges = false
+        fetchRequest.shouldRefreshRefetchedObjects = true
         
         let fetchedResultsController = NSFetchedResultsController(
+            dataStack: dataStack,
             fetchRequest: fetchRequest,
-            managedObjectContext: context,
-            sectionNameKeyPath: nil,
-            cacheName: nil
+            fetchClauses: [Where("SELF", isEqualTo: object.objectID)]
         )
         
         let fetchedResultsControllerDelegate = FetchedResultsControllerDelegate()
         
-        self.originalObjectID = originalObjectID
         self.fetchedResultsController = fetchedResultsController
         self.fetchedResultsControllerDelegate = fetchedResultsControllerDelegate
         self.parentStack = dataStack
@@ -207,15 +194,23 @@ public final class ObjectMonitor<T: NSManagedObject> {
         self.lastCommittedAttributes = (self.object?.committedValuesForKeys(nil) as? [String: NSObject]) ?? [:]
     }
     
+    deinit {
+        
+        self.fetchedResultsControllerDelegate.fetchedResultsController = nil
+    }
+    
     
     // MARK: Private
     
-    private let originalObjectID: NSManagedObjectID
     private let fetchedResultsController: NSFetchedResultsController
     private let fetchedResultsControllerDelegate: FetchedResultsControllerDelegate
     private var lastCommittedAttributes = [String: NSObject]()
     private weak var parentStack: DataStack?
     
+    private var willChangeObjectKey: Void?
+    private var didDeleteObjectKey: Void?
+    private var didUpdateObjectKey: Void?
+    
     private func registerChangeNotification(notificationKey: UnsafePointer<Void>, name: String, toObserver observer: AnyObject, callback: (monitor: ObjectMonitor<T>) -> Void) {
         
         setAssociatedRetainedObject(
@@ -224,10 +219,11 @@ public final class ObjectMonitor<T: NSManagedObject> {
                 object: self,
                 closure: { [weak self] (note) -> Void in
                     
-                    if let strongSelf = self {
+                    guard let strongSelf = self else {
                         
-                        callback(monitor: strongSelf)
+                        return
                     }
+                    callback(monitor: strongSelf)
                 }
             ),
             forKey: notificationKey,
@@ -243,15 +239,13 @@ public final class ObjectMonitor<T: NSManagedObject> {
                 object: self,
                 closure: { [weak self] (note) -> Void in
                     
-                    if let strongSelf = self,
+                    guard let strongSelf = self,
                         let userInfo = note.userInfo,
-                        let object = userInfo[UserInfoKeyObject] as? T {
+                        let object = userInfo[UserInfoKeyObject] as? T else {
                             
-                            callback(
-                                monitor: strongSelf,
-                                object: object
-                            )
+                            return
                     }
+                    callback(monitor: strongSelf, object: object)
                 }
             ),
             forKey: notificationKey,
@@ -261,13 +255,36 @@ public final class ObjectMonitor<T: NSManagedObject> {
 }
 
 
+// MARK: - ObjectMonitor: Equatable
+
+@available(OSX, unavailable)
+public func ==<T: NSManagedObject>(lhs: ObjectMonitor<T>, rhs: ObjectMonitor<T>) -> Bool {
+    
+    return lhs === rhs
+}
+
+@available(OSX, unavailable)
+extension ObjectMonitor: Equatable { }
+
+
 // MARK: - ObjectMonitor: FetchedResultsControllerHandler
 
+@available(OSX, unavailable)
 extension ObjectMonitor: FetchedResultsControllerHandler {
     
     // MARK: FetchedResultsControllerHandler
     
-    private func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
+    internal func controllerWillChangeContent(controller: NSFetchedResultsController) {
+        
+        NSNotificationCenter.defaultCenter().postNotificationName(
+            ObjectMonitorWillChangeObjectNotification,
+            object: self
+        )
+    }
+    
+    internal func controllerDidChangeContent(controller: NSFetchedResultsController) { }
+    
+    internal func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
         
         switch type {
             
@@ -290,57 +307,18 @@ extension ObjectMonitor: FetchedResultsControllerHandler {
         }
     }
     
-    private func controllerWillChangeContent(controller: NSFetchedResultsController) {
+    internal func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) { }
+    
+    internal func controller(controller: NSFetchedResultsController, sectionIndexTitleForSectionName sectionName: String?) -> String? {
         
-        NSNotificationCenter.defaultCenter().postNotificationName(
-            ObjectMonitorWillChangeObjectNotification,
-            object: self
-        )
+        return sectionName
     }
 }
 
 
-// MARK: - FetchedResultsControllerHandler
+private let ObjectMonitorWillChangeObjectNotification = "ObjectMonitorWillChangeObjectNotification"
+private let ObjectMonitorDidDeleteObjectNotification = "ObjectMonitorDidDeleteObjectNotification"
+private let ObjectMonitorDidUpdateObjectNotification = "ObjectMonitorDidUpdateObjectNotification"
 
-private protocol FetchedResultsControllerHandler: class {
-    
-    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?)
-    
-    func controllerWillChangeContent(controller: NSFetchedResultsController)
-}
+private let UserInfoKeyObject = "UserInfoKeyObject"
 
-
-// MARK: - FetchedResultsControllerDelegate
-
-private final class FetchedResultsControllerDelegate: NSObject, NSFetchedResultsControllerDelegate {
-    
-    // MARK: NSFetchedResultsControllerDelegate
-    
-    @objc dynamic func controllerWillChangeContent(controller: NSFetchedResultsController) {
-        
-        self.handler?.controllerWillChangeContent(controller)
-    }
-    
-    @objc dynamic func controller(controller: NSFetchedResultsController, didChangeObject anObject: NSManagedObject, 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/ObjectObserver.swift

@@ -35,12 +35,13 @@ Implement the `ObjectObserver` protocol to observe changes to a single `NSManage
     let monitor = CoreStore.monitorObject(object)
     monitor.addObserver(self)
 */
+@available(OSX, unavailable)
 public protocol ObjectObserver: class {
     
     /**
     The `NSManagedObject` type for the observed object
     */
-    typealias EntityType: NSManagedObject
+    typealias ObjectEntityType: NSManagedObject
     
     /**
     Handles processing just before a change to the observed `object` occurs
@@ -48,7 +49,7 @@ public protocol ObjectObserver: class {
     - parameter monitor: the `ObjectMonitor` monitoring the object being observed
     - parameter object: the `NSManagedObject` instance being observed
     */
-    func objectMonitor(monitor: ObjectMonitor<EntityType>, willUpdateObject object: EntityType)
+    func objectMonitor(monitor: ObjectMonitor<ObjectEntityType>, willUpdateObject object: ObjectEntityType)
     
     /**
     Handles processing right after a change to the observed `object` occurs
@@ -57,7 +58,7 @@ public protocol ObjectObserver: class {
     - parameter object: the `NSManagedObject` instance being observed
     - parameter 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 objectMonitor(monitor: ObjectMonitor<EntityType>, didUpdateObject object: EntityType, changedPersistentKeys: Set<KeyPath>)
+    func objectMonitor(monitor: ObjectMonitor<ObjectEntityType>, didUpdateObject object: ObjectEntityType, changedPersistentKeys: Set<KeyPath>)
     
     /**
     Handles processing right after `object` is deleted
@@ -65,5 +66,27 @@ public protocol ObjectObserver: class {
     - parameter monitor: the `ObjectMonitor` monitoring the object being observed
     - parameter object: the `NSManagedObject` instance being observed
     */
-    func objectMonitor(monitor: ObjectMonitor<EntityType>, didDeleteObject object: EntityType)
+    func objectMonitor(monitor: ObjectMonitor<ObjectEntityType>, didDeleteObject object: ObjectEntityType)
+}
+
+
+// MARK: - ObjectObserver (Default Implementations)
+
+@available(OSX, unavailable)
+public extension ObjectObserver {
+    
+    /**
+    The default implementation does nothing.
+    */
+    func objectMonitor(monitor: ObjectMonitor<ObjectEntityType>, willUpdateObject object: ObjectEntityType) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func objectMonitor(monitor: ObjectMonitor<ObjectEntityType>, didUpdateObject object: ObjectEntityType, changedPersistentKeys: Set<KeyPath>) { }
+    
+    /**
+    The default implementation does nothing.
+    */
+    func objectMonitor(monitor: ObjectMonitor<ObjectEntityType>, didDeleteObject object: ObjectEntityType) { }
 }

CoreStore/Observing/SectionBy.swift

@@ -38,6 +38,7 @@ The `SectionBy` clause indicates the key path to use to group the `ListMonitor`
         OrderBy(.Ascending("lastName"))
     )
 */
+@available(OSX, unavailable)
 public struct SectionBy {
     
     // MARK: Public

CoreStore/Saving and Processing/AsynchronousDataTransaction.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - AsynchronousDataTransaction
@@ -54,14 +56,15 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
         )
         
         self.isCommitted = true
-        let semaphore = GCDSemaphore(0)
+        let group = GCDGroup()
+        group.enter()
         self.context.saveAsynchronouslyWithCompletion { (result) -> Void in
             
             self.result = result
             completion(result: result)
-            semaphore.signal()
+            group.leave()
         }
-        semaphore.wait()
+        group.wait()
     }
     
     /**
@@ -112,6 +115,7 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
     - parameter object: the `NSManagedObject` type to be edited
     - returns: an editable proxy for the specified `NSManagedObject`.
     */
+    @warn_unused_result
     public override func edit<T: NSManagedObject>(object: T?) -> T? {
         
         CoreStore.assert(
@@ -129,6 +133,7 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
     - parameter objectID: the `NSManagedObjectID` for the object to be edited
     - returns: an editable proxy for the specified `NSManagedObject`.
     */
+    @warn_unused_result
     public override func edit<T: NSManagedObject>(into: Into<T>, _ objectID: NSManagedObjectID) -> T? {
         
         CoreStore.assert(
@@ -168,7 +173,7 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
             "Attempted to delete an entities from an already committed \(typeName(self))."
         )
         
-        super.delete([object1, object2] + objects)
+        super.delete(([object1, object2] + objects).flatMap { $0 })
     }
     
     /**
@@ -176,7 +181,7 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
     
     - parameter objects: the `NSManagedObject`s type to be deleted
     */
-    public override func delete(objects: [NSManagedObject?]) {
+    public override func delete<S: SequenceType where S.Generator.Element: NSManagedObject>(objects: S) {
         
         CoreStore.assert(
             !self.isCommitted,
@@ -187,16 +192,21 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
     }
     
     /**
-    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() {
+     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.
+     */
+    @available(*, deprecated=1.3.4, message="Resetting the context is inherently unsafe. This method will be removed in the near future. Use `beginUnsafe()` to create transactions with `undo` support.")
+    public func rollback() {
         
         CoreStore.assert(
             !self.isCommitted,
             "Attempted to rollback an already committed \(typeName(self))."
         )
+        CoreStore.assert(
+            self.transactionQueue.isCurrentExecutionContext(),
+            "Attempted to rollback a \(typeName(self)) outside its designated queue."
+        )
         
-        super.rollback()
+        self.context.reset()
     }
     
     
@@ -206,7 +216,7 @@ public final class AsynchronousDataTransaction: BaseDataTransaction {
         
         self.closure = closure
         
-        super.init(mainContext: mainContext, queue: queue)
+        super.init(mainContext: mainContext, queue: queue, supportsUndo: false, bypassesQueueing: false)
     }
     
     internal func perform() {

CoreStore/Saving and Processing/BaseDataTransaction.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - BaseDataTransaction
@@ -104,14 +106,18 @@ public /*abstract*/ class BaseDataTransaction {
     - parameter object: the `NSManagedObject` type to be edited
     - returns: an editable proxy for the specified `NSManagedObject`.
     */
+    @warn_unused_result
     public func edit<T: NSManagedObject>(object: T?) -> T? {
         
         CoreStore.assert(
             self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to update an entity of type \(typeName(object)) outside its designated queue."
         )
-        
-        return object?.inContext(self.context)
+        guard let object = object else {
+            
+            return nil
+        }
+        return self.context.fetchExisting(object)
     }
     
     /**
@@ -121,6 +127,7 @@ public /*abstract*/ class BaseDataTransaction {
     - parameter objectID: the `NSManagedObjectID` for the object to be edited
     - returns: an editable proxy for the specified `NSManagedObject`.
     */
+    @warn_unused_result
     public func edit<T: NSManagedObject>(into: Into<T>, _ objectID: NSManagedObjectID) -> T? {
         
         CoreStore.assert(
@@ -132,8 +139,7 @@ public /*abstract*/ class BaseDataTransaction {
                 || (into.configuration ?? Into.defaultConfigurationName) == objectID.persistentStore?.configurationName,
             "Attempted to update an entity of type \(typeName(T)) but the specified persistent store do not match the `NSManagedObjectID`."
         )
-        
-        return (into.entityClass as! NSManagedObject.Type).inContext(self.context, withObjectID: objectID) as? T
+        return self.fetchExisting(objectID) as? T
     }
     
     /**
@@ -147,8 +153,11 @@ public /*abstract*/ class BaseDataTransaction {
             self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
             "Attempted to delete an entity outside its designated queue."
         )
-        
-        object?.inContext(self.context)?.deleteFromContext()
+        guard let object = object else {
+            
+            return
+        }
+        self.context.fetchExisting(object)?.deleteFromContext()
     }
     
     /**
@@ -160,7 +169,7 @@ public /*abstract*/ class BaseDataTransaction {
     */
     public func delete(object1: NSManagedObject?, _ object2: NSManagedObject?, _ objects: NSManagedObject?...) {
         
-        self.delete([object1, object2] + objects)
+        self.delete(([object1, object2] + objects).flatMap { $0 })
     }
     
     /**
@@ -168,7 +177,7 @@ public /*abstract*/ class BaseDataTransaction {
     
     - parameter objects: the `NSManagedObject`s to be deleted
     */
-    public func delete(objects: [NSManagedObject?]) {
+    public func delete<S: SequenceType where S.Generator.Element: NSManagedObject>(objects: S) {
         
         CoreStore.assert(
             self.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
@@ -176,25 +185,7 @@ public /*abstract*/ class BaseDataTransaction {
         )
         
         let context = self.context
-        for object in objects {
-            
-            object?.inContext(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.bypassesQueueing || self.transactionQueue.isCurrentExecutionContext(),
-            "Attempted to rollback a \(typeName(self)) outside its designated queue."
-        )
-        
-        self.context.reset()
+        objects.forEach { context.fetchExisting($0)?.deleteFromContext() }
     }
     
     
@@ -203,26 +194,33 @@ public /*abstract*/ class BaseDataTransaction {
     internal let context: NSManagedObjectContext
     internal let transactionQueue: GCDQueue
     internal let childTransactionQueue: GCDQueue = .createSerial("com.corestore.datastack.childtransactionqueue")
+    internal let supportsUndo: Bool
+    internal let bypassesQueueing: Bool
+    
     
     internal var isCommitted = false
     internal var result: SaveResult?
     
-    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue) {
-        
-        self.transactionQueue = queue
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue, supportsUndo: Bool, bypassesQueueing: Bool) {
         
         let context = mainContext.temporaryContextInTransactionWithConcurrencyType(
             queue == .Main
                 ? .MainQueueConcurrencyType
                 : .PrivateQueueConcurrencyType
         )
+        self.transactionQueue = queue
         self.context = context
+        self.supportsUndo = supportsUndo
+        self.bypassesQueueing = bypassesQueueing
         
         context.parentTransaction = self
-    }
-    
-    internal var bypassesQueueing: Bool {
-        
-        return false
+        if !supportsUndo {
+            
+            context.undoManager = nil
+        }
+        else if context.undoManager == nil {
+            
+            context.undoManager = NSUndoManager()
+        }
     }
 }

CoreStore/Saving and Processing/CoreStore+Transaction.swift

@@ -43,23 +43,32 @@ public extension CoreStore {
     }
     
     /**
-    Using the `defaultStack`, begins a transaction asynchronously where `NSManagedObject` creates, updates, and deletes can be made.
-    
-    - parameter 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
-    */
+     Using the `defaultStack`, begins a transaction asynchronously where `NSManagedObject` creates, updates, and deletes can be made.
+     
+     - parameter 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 {
+     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. An unsafe transaction object should typically be only used from the main queue.
+     
+     - prameter supportsUndo: `undo()`, `redo()`, and `rollback()` methods are only available when this parameter is `true`, otherwise those method will raise an exception. Defaults to `false`. Note that turning on Undo support may heavily impact performance especially on iOS or watchOS where memory is limited.
+     - returns: a `UnsafeDataTransaction` instance where creates, updates, and deletes can be made.
+     */
+    @warn_unused_result
+    public static func beginUnsafe(supportsUndo supportsUndo: Bool = false) -> UnsafeDataTransaction {
         
-        return self.defaultStack.beginDetached()
+        return self.defaultStack.beginUnsafe(supportsUndo: supportsUndo)
+    }
+    
+    @available(*, deprecated=1.3.1, renamed="beginUnsafe")
+    @warn_unused_result
+    public static func beginDetached() -> UnsafeDataTransaction {
+        
+        return self.beginUnsafe()
     }
 }

CoreStore/Saving and Processing/DataStack+Transaction.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - DataStack
@@ -48,11 +50,11 @@ public extension DataStack {
     }
     
     /**
-    Begins a transaction synchronously where `NSManagedObject` creates, updates, and deletes can be made.
-    
-    - parameter 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
-    */
+     Begins a transaction synchronously where `NSManagedObject` creates, updates, and deletes can be made.
+     
+     - parameter 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? {
         
         return SynchronousDataTransaction(
@@ -62,18 +64,28 @@ public extension DataStack {
     }
     
     /**
-    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.
-    
-    - returns: a `DetachedDataTransaction` instance where creates, updates, and deletes can be made.
-    */
-    public func beginDetached() -> DetachedDataTransaction {
+     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.
+     
+     - prameter supportsUndo: `undo()`, `redo()`, and `rollback()` methods are only available when this parameter is `true`, otherwise those method will raise an exception. Defaults to `false`. Note that turning on Undo support may heavily impact performance especially on iOS or watchOS where memory is limited.
+     - returns: a `UnsafeDataTransaction` instance where creates, updates, and deletes can be made.
+     */
+    @warn_unused_result
+    public func beginUnsafe(supportsUndo supportsUndo: Bool = false) -> UnsafeDataTransaction {
         
-        return DetachedDataTransaction(
+        return UnsafeDataTransaction(
             mainContext: self.rootSavingContext,
             queue: .createSerial(
-                "com.coreStore.dataStack.detachedTransactionQueue",
+                "com.coreStore.dataStack.unsafeTransactionQueue",
                 targetQueue: .UserInitiated
-            )
+            ),
+            supportsUndo: supportsUndo
         )
     }
+    
+    @available(*, deprecated=1.3.1, renamed="beginUnsafe")
+    @warn_unused_result
+    public func beginDetached() -> UnsafeDataTransaction {
+        
+        return self.beginUnsafe()
+    }
 }

CoreStore/Saving and Processing/DetachedDataTransaction.swift

@@ -1,86 +0,0 @@
-//
-//  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
-    
-    /**
-    Returns the `NSManagedObjectContext` for this detached transaction. Use only for cases where external frameworks need an `NSManagedObjectContext` instance to work with.
-    
-    Note that it is the developer's responsibility to ensure the following:
-    - that the `DetachedDataTransaction` that owns this context should be strongly referenced and prevented from being deallocated during the context's lifetime
-    - that all saves will be done either through the `DetachedDataTransaction`'s `commit(...)` method, or by calling `save()` manually on the context, its parent, and all other ancestor contexts if there are any.
-    */
-    public var internalContext: NSManagedObjectContext {
-        
-        return self.context
-    }
-    
-    /**
-    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.
-    
-    - parameter 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) {
-        
-        self.context.saveAsynchronouslyWithCompletion { (result) -> Void in
-            
-            self.result = result
-            completion(result: result)
-        }
-    }
-    
-    /**
-    Begins a child transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms.
-    
-    - returns: a `DetachedDataTransaction` instance where creates, updates, and deletes can be made.
-    */
-    public func beginDetached() -> DetachedDataTransaction {
-        
-        return DetachedDataTransaction(
-            mainContext: self.context,
-            queue: self.transactionQueue
-        )
-    }
-    
-    
-    // MARK: Internal
-    
-    internal override var bypassesQueueing: Bool {
-        
-        return true
-    }
-}
-

CoreStore/Saving and Processing/Into.swift

@@ -36,7 +36,7 @@ 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"))
+    let person = transaction.create(Into<MyPersonEntity>("Configuration1"))
 
 This helps the `NSManagedObjectContext` to determine which
 */
@@ -48,7 +48,7 @@ public struct Into<T: NSManagedObject> {
     Initializes an `Into` clause.
     Sample Usage:
     
-    let person = transaction.create(Into<MyPersonEntity>())
+        let person = transaction.create(Into<MyPersonEntity>())
     */
     public init(){
         

CoreStore/Saving and Processing/SynchronousDataTransaction.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - SynchronousDataTransaction
@@ -103,6 +105,7 @@ public final class SynchronousDataTransaction: BaseDataTransaction {
     - parameter object: the `NSManagedObject` type to be edited
     - returns: an editable proxy for the specified `NSManagedObject`.
     */
+    @warn_unused_result
     public override func edit<T: NSManagedObject>(object: T?) -> T? {
         
         CoreStore.assert(
@@ -120,6 +123,7 @@ public final class SynchronousDataTransaction: BaseDataTransaction {
     - parameter objectID: the `NSManagedObjectID` for the object to be edited
     - returns: an editable proxy for the specified `NSManagedObject`.
     */
+    @warn_unused_result
     public override func edit<T: NSManagedObject>(into: Into<T>, _ objectID: NSManagedObjectID) -> T? {
         
         CoreStore.assert(
@@ -159,7 +163,7 @@ public final class SynchronousDataTransaction: BaseDataTransaction {
             "Attempted to delete an entities from an already committed \(typeName(self))."
         )
         
-        super.delete([object1, object2] + objects)
+        super.delete(([object1, object2] + objects).flatMap { $0 })
     }
     
     /**
@@ -167,7 +171,7 @@ public final class SynchronousDataTransaction: BaseDataTransaction {
     
     - parameter objects: the `NSManagedObject`s to be deleted
     */
-    public override func delete(objects: [NSManagedObject?]) {
+    public override func delete<S: SequenceType where S.Generator.Element: NSManagedObject>(objects: S) {
         
         CoreStore.assert(
             !self.isCommitted,
@@ -179,20 +183,32 @@ public final class SynchronousDataTransaction: BaseDataTransaction {
     
     /**
     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() {
+     */
+    @available(*, deprecated=1.3.4, message="Resetting the context is inherently unsafe. This method will be removed in the near future. Use `beginUnsafe()` to create transactions with `undo` support.")
+    public func rollback() {
         
         CoreStore.assert(
             !self.isCommitted,
             "Attempted to rollback an already committed \(typeName(self))."
         )
+        CoreStore.assert(
+            self.transactionQueue.isCurrentExecutionContext(),
+            "Attempted to rollback a \(typeName(self)) outside its designated queue."
+        )
         
-        super.rollback()
+        self.context.reset()
     }
     
     
     // MARK: Internal
     
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue, closure: (transaction: SynchronousDataTransaction) -> Void) {
+        
+        self.closure = closure
+        
+        super.init(mainContext: mainContext, queue: queue, supportsUndo: false, bypassesQueueing: false)
+    }
+    
     internal func performAndWait() -> SaveResult? {
         
         self.transactionQueue.sync {
@@ -210,13 +226,6 @@ public final class SynchronousDataTransaction: BaseDataTransaction {
         return self.result
     }
     
-    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue, closure: (transaction: SynchronousDataTransaction) -> Void) {
-        
-        self.closure = closure
-        
-        super.init(mainContext: mainContext, queue: queue)
-    }
-    
     
     // MARK: Private
     

CoreStore/Saving and Processing/UnsafeDataTransaction.swift

@@ -0,0 +1,138 @@
+//
+//  UnsafeDataTransaction.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
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
+
+
+@available(*, deprecated=1.3.1, renamed="UnsafeDataTransaction")
+public typealias DetachedDataTransaction = UnsafeDataTransaction
+
+
+// MARK: - UnsafeDataTransaction
+
+/**
+The `UnsafeDataTransaction` provides an interface for non-contiguous `NSManagedObject` creates, updates, and deletes. This is useful for making temporary changes, such as partially filled forms. An unsafe transaction object should typically be only used from the main queue.
+*/
+public final class UnsafeDataTransaction: BaseDataTransaction {
+    
+    // MARK: Public
+    
+    /**
+    Saves the transaction changes asynchronously. For a `UnsafeDataTransaction`, multiple commits are allowed, although it is the developer's responsibility to ensure a reasonable leeway to prevent blocking the main thread.
+    
+    - parameter 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) {
+        
+        self.context.saveAsynchronouslyWithCompletion { (result) -> Void in
+            
+            self.result = result
+            completion(result: result)
+        }
+    }
+    
+    /**
+     Rolls back the transaction.
+     */
+    public func rollback() {
+        
+        CoreStore.assert(
+            self.supportsUndo,
+            "Attempted to rollback a \(typeName(self)) with Undo support disabled."
+        )
+        self.context.rollback()
+    }
+    
+    /**
+     Undo's the last change made to the transaction.
+     */
+    public func undo() {
+        
+        CoreStore.assert(
+            self.supportsUndo,
+            "Attempted to undo a \(typeName(self)) with Undo support disabled."
+        )
+        self.context.undo()
+    }
+    
+    /**
+     Redo's the last undone change to the transaction.
+     */
+    public func redo() {
+        
+        CoreStore.assert(
+            self.supportsUndo,
+            "Attempted to redo a \(typeName(self)) with Undo support disabled."
+        )
+        self.context.redo()
+    }
+    
+    /**
+     Begins a child transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms.
+     
+     - prameter supportsUndo: `undo()`, `redo()`, and `rollback()` methods are only available when this parameter is `true`, otherwise those method will raise an exception. Defaults to `false`. Note that turning on Undo support may heavily impact performance especially on iOS or watchOS where memory is limited.
+     - returns: a `UnsafeDataTransaction` instance where creates, updates, and deletes can be made.
+     */
+    @warn_unused_result
+    public func beginUnsafe(supportsUndo supportsUndo: Bool = false) -> UnsafeDataTransaction {
+        
+        return UnsafeDataTransaction(
+            mainContext: self.context,
+            queue: self.transactionQueue,
+            supportsUndo: supportsUndo
+        )
+    }
+    
+    /**
+     Returns the `NSManagedObjectContext` for this unsafe transaction. Use only for cases where external frameworks need an `NSManagedObjectContext` instance to work with.
+     
+     Note that it is the developer's responsibility to ensure the following:
+     - that the `UnsafeDataTransaction` that owns this context should be strongly referenced and prevented from being deallocated during the context's lifetime
+     - that all saves will be done either through the `UnsafeDataTransaction`'s `commit(...)` method, or by calling `save()` manually on the context, its parent, and all other ancestor contexts if there are any.
+     */
+    public var internalContext: NSManagedObjectContext {
+        
+        return self.context
+    }
+    
+    @available(*, deprecated=1.3.1, renamed="beginUnsafe")
+    @warn_unused_result
+    public func beginDetached() -> UnsafeDataTransaction {
+        
+        return self.beginUnsafe()
+    }
+    
+    
+    // MARK: Internal
+    
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue, supportsUndo: Bool) {
+        
+        super.init(mainContext: mainContext, queue: queue, supportsUndo: supportsUndo, bypassesQueueing: true)
+    }
+}

CoreStore/Setting Up/CoreStore+Setup.swift

@@ -25,13 +25,39 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 // MARK: - CoreStore
 
 public extension CoreStore {
     
+    /**
+    Returns the `defaultStack`'s model version. The version string is the same as the name of the version-specific .xcdatamodeld file.
+    */
+    public static var modelVersion: String {
+        
+        return self.defaultStack.modelVersion
+    }
+    
+    /**
+    Returns the entity name-to-class type mapping from the `defaultStack`'s model.
+    */
+    public static var entityTypesByName: [String: NSManagedObject.Type] {
+        
+        return self.defaultStack.entityTypesByName
+    }
+    
+    /**
+    Returns the `NSEntityDescription` for the specified `NSManagedObject` subclass from `defaultStack`'s model.
+    */
+    public static func entityDescriptionForType(type: NSManagedObject.Type) -> NSEntityDescription? {
+        
+        return self.defaultStack.entityDescriptionForType(type)
+    }
+    
     /**
     Adds an in-memory store to the `defaultStack`.
     

CoreStore/Setting Up/DataStack.swift

@@ -25,7 +25,9 @@
 
 import Foundation
 import CoreData
-import GCDKit
+#if USE_FRAMEWORKS
+    import GCDKit
+#endif
 
 
 internal let applicationSupportDirectory = NSFileManager.defaultManager().URLsForDirectory(.ApplicationSupportDirectory, inDomains: .UserDomainMask).first!
@@ -81,6 +83,33 @@ public final class DataStack {
         return self.model.currentModelVersion!
     }
     
+    /**
+    Returns the entity name-to-class type mapping from the `DataStack`'s model.
+    */
+    public var entityTypesByName: [String: NSManagedObject.Type] {
+        
+        return self.model.entityTypesMapping()
+    }
+    
+    /**
+    Returns the `NSEntityDescription` for the specified `NSManagedObject` subclass.
+    */
+    public func entityDescriptionForType(type: NSManagedObject.Type) -> NSEntityDescription? {
+    
+        return NSEntityDescription.entityForName(
+            self.model.entityNameForClass(type),
+            inManagedObjectContext: self.mainContext
+        )
+    }
+    
+    /**
+    Returns the `NSManagedObjectID` for the specified object URI if it exists in the persistent store.
+    */
+    public func objectIDForURIRepresentation(url: NSURL) -> NSManagedObjectID? {
+        
+        return self.coordinator.managedObjectIDForURIRepresentation(url)
+    }
+    
     /**
     Adds an in-memory store to the stack.
     
@@ -162,34 +191,31 @@ public final class DataStack {
         let coordinator = self.coordinator;
         if let store = coordinator.persistentStoreForURL(fileURL) {
             
-            if store.type == NSSQLiteStoreType
-                && store.configurationName == (configuration ?? Into.defaultConfigurationName) {
+            guard store.type == NSSQLiteStoreType
+                && store.configurationName == (configuration ?? Into.defaultConfigurationName) else {
                     
-                    return store
+                    let error = NSError(coreStoreErrorCode: .DifferentPersistentStoreExistsAtURL)
+                    CoreStore.handleError(
+                        error,
+                        "Failed to add SQLite \(typeName(NSPersistentStore)) at \"\(fileURL)\" because a different \(typeName(NSPersistentStore)) at that URL already exists."
+                    )
+                    
+                    throw error
             }
             
-            let error = NSError(coreStoreErrorCode: .DifferentPersistentStoreExistsAtURL)
-            CoreStore.handleError(
-                error,
-                "Failed to add SQLite \(typeName(NSPersistentStore)) at \"\(fileURL)\" because a different \(typeName(NSPersistentStore)) at that URL already exists."
-            )
-            
-            throw error
+            return store
         }
         
         let fileManager = NSFileManager.defaultManager()
-        do {
-            
-            try fileManager.createDirectoryAtURL(
-                fileURL.URLByDeletingLastPathComponent!,
-                withIntermediateDirectories: true,
-                attributes: nil
-            )
-        }
-        catch _ { }
+        _ = try? fileManager.createDirectoryAtURL(
+            fileURL.URLByDeletingLastPathComponent!,
+            withIntermediateDirectories: true,
+            attributes: nil
+        )
         
         var store: NSPersistentStore?
         var storeError: NSError?
+        let options = self.optionsForSQLiteStore()
         coordinator.performBlockAndWait {
             
             do {
@@ -198,7 +224,7 @@ public final class DataStack {
                     NSSQLiteStoreType,
                     configuration: configuration,
                     URL: fileURL,
-                    options: [NSSQLitePragmasOption: ["journal_mode": "WAL"]]
+                    options: options
                 )
             }
             catch {
@@ -270,6 +296,11 @@ public final class DataStack {
         return migrationQueue
     }()
     
+    internal func optionsForSQLiteStore() -> [String: AnyObject] {
+        
+        return [NSSQLitePragmasOption: ["journal_mode": "WAL"]]
+    }
+    
     internal func entityNameForEntityClass(entityClass: AnyClass) -> String? {
         
         return self.model.entityNameForClass(entityClass)
@@ -350,11 +381,7 @@ public final class DataStack {
         
         for store in self.coordinator.persistentStores {
             
-            do {
-                
-                try self.coordinator.removePersistentStore(store)
-            }
-            catch _ { }
+            _ = try? self.coordinator.removePersistentStore(store)
         }
     }
 }

CoreStoreDemo/CoreStoreDemo.xcodeproj/project.pbxproj

@@ -35,10 +35,10 @@
 		B569651A1B30888A0075EE4A /* FetchingResultsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = B56965191B30888A0075EE4A /* FetchingResultsViewController.swift */; };
 		B569651C1B30889A0075EE4A /* QueryingResultsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = B569651B1B30889A0075EE4A /* QueryingResultsViewController.swift */; };
 		B56965291B3582D30075EE4A /* MigrationDemo.xcdatamodeld in Sources */ = {isa = PBXBuildFile; fileRef = B56965271B3582D30075EE4A /* MigrationDemo.xcdatamodeld */; };
-		B583A9201AF5F542001F76AF /* CoreStore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B583A91B1AF5F4F4001F76AF /* CoreStore.framework */; };
-		B583A9211AF5F542001F76AF /* CoreStore.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = B583A91B1AF5F4F4001F76AF /* CoreStore.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
-		B5D9C9191B20AB1900E64F0E /* GCDKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B5D9C9181B20AB1900E64F0E /* GCDKit.framework */; };
-		B5D9C91A1B20AB1900E64F0E /* GCDKit.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = B5D9C9181B20AB1900E64F0E /* GCDKit.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		B5BDC9221C202429008147CD /* CoreStore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B5BDC9211C202429008147CD /* CoreStore.framework */; };
+		B5BDC9231C202429008147CD /* CoreStore.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = B5BDC9211C202429008147CD /* CoreStore.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		B5BDC9251C202429008147CD /* GCDKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B5BDC9241C202429008147CD /* GCDKit.framework */; };
+		B5BDC9261C202429008147CD /* GCDKit.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = B5BDC9241C202429008147CD /* GCDKit.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		B5E599321B5240F50084BD5F /* OrganismTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5E599311B5240F50084BD5F /* OrganismTableViewCell.swift */; };
 		B5EE25851B36E23C0000406B /* OrganismV1.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5EE25841B36E23C0000406B /* OrganismV1.swift */; };
 		B5EE25871B36E2520000406B /* OrganismV2.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5EE25861B36E2520000406B /* OrganismV2.swift */; };
@@ -47,37 +47,6 @@
 		B5EE259E1B3EC1B20000406B /* OrganismProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5EE259D1B3EC1B20000406B /* OrganismProtocol.swift */; };
 /* End PBXBuildFile section */
 
-/* Begin PBXContainerItemProxy section */
-		B583A91A1AF5F4F4001F76AF /* PBXContainerItemProxy */ = {
-			isa = PBXContainerItemProxy;
-			containerPortal = B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */;
-			proxyType = 2;
-			remoteGlobalIDString = 2F03A53019C5C6DA005002A5;
-			remoteInfo = CoreStore;
-		};
-		B583A91C1AF5F4F4001F76AF /* PBXContainerItemProxy */ = {
-			isa = PBXContainerItemProxy;
-			containerPortal = B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */;
-			proxyType = 2;
-			remoteGlobalIDString = 2F03A53B19C5C6DA005002A5;
-			remoteInfo = CoreStoreTests;
-		};
-		B583A91E1AF5F512001F76AF /* PBXContainerItemProxy */ = {
-			isa = PBXContainerItemProxy;
-			containerPortal = B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */;
-			proxyType = 1;
-			remoteGlobalIDString = 2F03A52F19C5C6DA005002A5;
-			remoteInfo = CoreStore;
-		};
-		B583A9221AF5F542001F76AF /* PBXContainerItemProxy */ = {
-			isa = PBXContainerItemProxy;
-			containerPortal = B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */;
-			proxyType = 1;
-			remoteGlobalIDString = 2F03A52F19C5C6DA005002A5;
-			remoteInfo = CoreStore;
-		};
-/* End PBXContainerItemProxy section */
-
 /* Begin PBXCopyFilesBuildPhase section */
 		B583A9241AF5F542001F76AF /* Embed Frameworks */ = {
 			isa = PBXCopyFilesBuildPhase;
@@ -85,8 +54,8 @@
 			dstPath = "";
 			dstSubfolderSpec = 10;
 			files = (
-				B5D9C91A1B20AB1900E64F0E /* GCDKit.framework in Embed Frameworks */,
-				B583A9211AF5F542001F76AF /* CoreStore.framework in Embed Frameworks */,
+				B5BDC9261C202429008147CD /* GCDKit.framework in Embed Frameworks */,
+				B5BDC9231C202429008147CD /* CoreStore.framework in Embed Frameworks */,
 			);
 			name = "Embed Frameworks";
 			runOnlyForDeploymentPostprocessing = 0;
@@ -124,8 +93,8 @@
 		B56965191B30888A0075EE4A /* FetchingResultsViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FetchingResultsViewController.swift; sourceTree = "<group>"; };
 		B569651B1B30889A0075EE4A /* QueryingResultsViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = QueryingResultsViewController.swift; sourceTree = "<group>"; };
 		B56965281B3582D30075EE4A /* MigrationDemo.xcdatamodel */ = {isa = PBXFileReference; lastKnownFileType = wrapper.xcdatamodel; path = MigrationDemo.xcdatamodel; sourceTree = "<group>"; };
-		B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = CoreStore.xcodeproj; path = ../CoreStore.xcodeproj; sourceTree = "<group>"; };
-		B5D9C9181B20AB1900E64F0E /* GCDKit.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = GCDKit.framework; sourceTree = BUILT_PRODUCTS_DIR; };
+		B5BDC9211C202429008147CD /* CoreStore.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; name = CoreStore.framework; path = "/Users/JohnEstropia/Library/Developer/Xcode/DerivedData/Build/Products/Debug-iphoneos/CoreStore.framework"; sourceTree = "<absolute>"; };
+		B5BDC9241C202429008147CD /* GCDKit.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; name = GCDKit.framework; path = "/Users/JohnEstropia/Library/Developer/Xcode/DerivedData/Build/Products/Debug-iphoneos/GCDKit.framework"; sourceTree = "<absolute>"; };
 		B5E599311B5240F50084BD5F /* OrganismTableViewCell.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = OrganismTableViewCell.swift; path = "CoreStoreDemo/MIgrations Demo/OrganismTableViewCell.swift"; sourceTree = SOURCE_ROOT; };
 		B5EE25801B36E1B00000406B /* MigrationDemoV2.xcdatamodel */ = {isa = PBXFileReference; lastKnownFileType = wrapper.xcdatamodel; path = MigrationDemoV2.xcdatamodel; sourceTree = "<group>"; };
 		B5EE25841B36E23C0000406B /* OrganismV1.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OrganismV1.swift; sourceTree = "<group>"; };
@@ -142,9 +111,9 @@
 			buildActionMask = 2147483647;
 			files = (
 				B52977E11B120F8A003D50A5 /* CoreLocation.framework in Frameworks */,
+				B5BDC9221C202429008147CD /* CoreStore.framework in Frameworks */,
+				B5BDC9251C202429008147CD /* GCDKit.framework in Frameworks */,
 				B52977DF1B120F83003D50A5 /* MapKit.framework in Frameworks */,
-				B5D9C9191B20AB1900E64F0E /* GCDKit.framework in Frameworks */,
-				B583A9201AF5F542001F76AF /* CoreStore.framework in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -175,9 +144,9 @@
 		B52977E21B120F90003D50A5 /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
-				B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */,
-				B5D9C9181B20AB1900E64F0E /* GCDKit.framework */,
 				B52977E01B120F8A003D50A5 /* CoreLocation.framework */,
+				B5BDC9211C202429008147CD /* CoreStore.framework */,
+				B5BDC9241C202429008147CD /* GCDKit.framework */,
 				B52977DE1B120F83003D50A5 /* MapKit.framework */,
 			);
 			name = Frameworks;
@@ -275,15 +244,6 @@
 			path = "Migrations Demo";
 			sourceTree = "<group>";
 		};
-		B583A9151AF5F4F3001F76AF /* Products */ = {
-			isa = PBXGroup;
-			children = (
-				B583A91B1AF5F4F4001F76AF /* CoreStore.framework */,
-				B583A91D1AF5F4F4001F76AF /* CoreStoreTests.xctest */,
-			);
-			name = Products;
-			sourceTree = "<group>";
-		};
 /* End PBXGroup section */
 
 /* Begin PBXNativeTarget section */
@@ -299,8 +259,6 @@
 			buildRules = (
 			);
 			dependencies = (
-				B583A91F1AF5F512001F76AF /* PBXTargetDependency */,
-				B583A9231AF5F542001F76AF /* PBXTargetDependency */,
 			);
 			name = CoreStoreDemo;
 			productName = CoreStoreDemo;
@@ -333,12 +291,6 @@
 			mainGroup = B54AAD401AF4D26E00848AE0;
 			productRefGroup = B54AAD4A1AF4D26E00848AE0 /* Products */;
 			projectDirPath = "";
-			projectReferences = (
-				{
-					ProductGroup = B583A9151AF5F4F3001F76AF /* Products */;
-					ProjectRef = B583A9141AF5F4F3001F76AF /* CoreStore.xcodeproj */;
-				},
-			);
 			projectRoot = "";
 			targets = (
 				B54AAD481AF4D26E00848AE0 /* CoreStoreDemo */,
@@ -346,23 +298,6 @@
 		};
 /* End PBXProject section */
 
-/* Begin PBXReferenceProxy section */
-		B583A91B1AF5F4F4001F76AF /* CoreStore.framework */ = {
-			isa = PBXReferenceProxy;
-			fileType = wrapper.framework;
-			path = CoreStore.framework;
-			remoteRef = B583A91A1AF5F4F4001F76AF /* PBXContainerItemProxy */;
-			sourceTree = BUILT_PRODUCTS_DIR;
-		};
-		B583A91D1AF5F4F4001F76AF /* CoreStoreTests.xctest */ = {
-			isa = PBXReferenceProxy;
-			fileType = wrapper.cfbundle;
-			path = CoreStoreTests.xctest;
-			remoteRef = B583A91C1AF5F4F4001F76AF /* PBXContainerItemProxy */;
-			sourceTree = BUILT_PRODUCTS_DIR;
-		};
-/* End PBXReferenceProxy section */
-
 /* Begin PBXResourcesBuildPhase section */
 		B54AAD471AF4D26E00848AE0 /* Resources */ = {
 			isa = PBXResourcesBuildPhase;
@@ -415,19 +350,6 @@
 		};
 /* End PBXSourcesBuildPhase section */
 
-/* Begin PBXTargetDependency section */
-		B583A91F1AF5F512001F76AF /* PBXTargetDependency */ = {
-			isa = PBXTargetDependency;
-			name = CoreStore;
-			targetProxy = B583A91E1AF5F512001F76AF /* PBXContainerItemProxy */;
-		};
-		B583A9231AF5F542001F76AF /* PBXTargetDependency */ = {
-			isa = PBXTargetDependency;
-			name = CoreStore;
-			targetProxy = B583A9221AF5F542001F76AF /* PBXContainerItemProxy */;
-		};
-/* End PBXTargetDependency section */
-
 /* Begin PBXVariantGroup section */
 		B54AAD571AF4D26E00848AE0 /* Main.storyboard */ = {
 			isa = PBXVariantGroup;

CoreStoreDemo/CoreStoreDemo/List and Object Observers Demo/ListObserverDemoViewController.swift

@@ -12,6 +12,41 @@ import CoreStore
 
 private struct Static {
     
+    enum Filter: String {
+        
+        case All = "All Colors"
+        case Light = "Light Colors"
+        case Dark = "Dark Colors"
+        
+        func next() -> Filter {
+            
+            switch self {
+                
+            case All: return .Light
+            case Light: return .Dark
+            case Dark: return .All
+            }
+        }
+        
+        func whereClause() -> Where {
+            
+            switch self {
+                
+            case .All: return Where(true)
+            case .Light: return Where("brightness >= 0.9")
+            case .Dark: return Where("brightness <= 0.4")
+            }
+        }
+    }
+    
+    static var filter = Filter.All {
+        
+        didSet {
+            
+            self.palettes.refetch(self.filter.whereClause())
+        }
+    }
+    
     static let palettes: ListMonitor<Palette> = {
         
         try! CoreStore.addSQLiteStoreAndWait(
@@ -47,7 +82,8 @@ class ListObserverDemoViewController: UITableViewController, ListSectionObserver
         
         super.viewDidLoad()
         
-        self.navigationItem.leftBarButtonItems = [
+        let navigationItem = self.navigationItem
+        navigationItem.leftBarButtonItems = [
             self.editButtonItem(),
             UIBarButtonItem(
                 barButtonSystemItem: .Trash,
@@ -55,13 +91,26 @@ class ListObserverDemoViewController: UITableViewController, ListSectionObserver
                 action: "resetBarButtonItemTouched:"
             )
         ]
-        self.navigationItem.rightBarButtonItem = UIBarButtonItem(
-            barButtonSystemItem: .Add,
+        
+        let filterBarButton = UIBarButtonItem(
+            title: Static.filter.rawValue,
+            style: .Plain,
             target: self,
-            action: "addBarButtonItemTouched:"
+            action: "filterBarButtonItemTouched:"
         )
+        navigationItem.rightBarButtonItems = [
+            UIBarButtonItem(
+                barButtonSystemItem: .Add,
+                target: self,
+                action: "addBarButtonItemTouched:"
+            ),
+            filterBarButton
+        ]
+        self.filterBarButton = filterBarButton
         
         Static.palettes.addObserver(self)
+        
+        self.setTableEnabled(!Static.palettes.isPendingRefetch)
     }
     
     override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
@@ -150,6 +199,18 @@ class ListObserverDemoViewController: UITableViewController, ListSectionObserver
         self.tableView.endUpdates()
     }
     
+    func listMonitorWillRefetch(monitor: ListMonitor<Palette>) {
+        
+        self.setTableEnabled(false)
+    }
+    
+    func listMonitorDidRefetch(monitor: ListMonitor<Palette>) {
+        
+        self.filterBarButton?.title = Static.filter.rawValue
+        self.tableView.reloadData()
+        self.setTableEnabled(true)
+    }
+    
     
     // MARK: ListObjectObserver
     
@@ -195,6 +256,8 @@ class ListObserverDemoViewController: UITableViewController, ListSectionObserver
     
     // MARK: Private
     
+    private var filterBarButton: UIBarButtonItem?
+    
     @IBAction private dynamic func resetBarButtonItemTouched(sender: AnyObject?) {
         
         CoreStore.beginAsynchronous { (transaction) -> Void in
@@ -204,6 +267,11 @@ class ListObserverDemoViewController: UITableViewController, ListSectionObserver
         }
     }
     
+    @IBAction private dynamic func filterBarButtonItemTouched(sender: AnyObject?) {
+        
+        Static.filter = Static.filter.next()
+    }
+    
     @IBAction private dynamic func addBarButtonItemTouched(sender: AnyObject?) {
         
         CoreStore.beginAsynchronous { (transaction) -> Void in
@@ -214,5 +282,23 @@ class ListObserverDemoViewController: UITableViewController, ListSectionObserver
             transaction.commit()
         }
     }
+    
+    private func setTableEnabled(enabled: Bool) {
+        
+        UIView.animateWithDuration(
+            0.2,
+            delay: 0,
+            options: .BeginFromCurrentState,
+            animations: { () -> Void in
+                
+                if let tableView = self.tableView {
+                    
+                    tableView.alpha = enabled ? 1.0 : 0.5
+                    tableView.userInteractionEnabled = enabled
+                }
+            },
+            completion: nil
+        )
+    }
 }
 

CoreStoreDemo/CoreStoreDemo/List and Object Observers Demo/ObjectObserverDemoViewController.swift

@@ -22,6 +22,11 @@ class ObjectObserverDemoViewController: UIViewController, ObjectObserver {
         }
         set {
             
+            guard self.monitor?.object != newValue else {
+                
+                return
+            }
+            
             if let palette = newValue {
                 
                 self.monitor = CoreStore.monitorObject(palette)
@@ -80,11 +85,6 @@ class ObjectObserverDemoViewController: UIViewController, ObjectObserver {
     
     // MARK: ObjectObserver
     
-    func objectMonitor(monitor: ObjectMonitor<Palette>, willUpdateObject object: Palette) {
-        
-        // none
-    }
-    
     func objectMonitor(monitor: ObjectMonitor<Palette>, didUpdateObject object: Palette, changedPersistentKeys: Set<KeyPath>) {
         
         self.reloadPaletteInfo(object, changedKeys: changedPersistentKeys)

CoreStoreDemo/CoreStoreDemo/Loggers Demo/CustomLoggerViewController.swift

@@ -62,7 +62,7 @@ class CustomLoggerViewController: UIViewController, CoreStoreLogger {
             case .Warning: levelString = "Warning"
             case .Fatal: levelString = "Fatal"
             }
-            self?.textView?.insertText("\(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Log:\(levelString)] \(message)\n\n")
+            self?.textView?.insertText("\((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Log:\(levelString)] \(message)\n\n")
         }
     }
     
@@ -70,7 +70,7 @@ class CustomLoggerViewController: UIViewController, CoreStoreLogger {
         
         GCDQueue.Main.async { [weak self] in
             
-            self?.textView?.insertText("\(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Error] \(message): \(error)\n\n")
+            self?.textView?.insertText("\((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Error] \(message): \(error)\n\n")
         }
     }
     
@@ -83,13 +83,13 @@ class CustomLoggerViewController: UIViewController, CoreStoreLogger {
         
         GCDQueue.Main.async { [weak self] in
             
-            self?.textView?.insertText("\(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Assert] \(message)\n\n")
+            self?.textView?.insertText("\((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Assert] \(message)\n\n")
         }
     }
     
     @noreturn func fatalError(message: String, fileName: StaticString, lineNumber: Int, functionName: StaticString) {
         
-        Swift.fatalError("\(fileName.stringValue.lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Abort] \(message)")
+        Swift.fatalError("\((fileName.stringValue as NSString).lastPathComponent):\(lineNumber) \(functionName)\n  ↪︎ [Abort] \(message)")
     }
     
     

CoreStoreDemo/CoreStoreDemo/MIgrations Demo/MigrationsDemoViewController.swift

@@ -285,7 +285,7 @@ class MigrationsDemoViewController: UIViewController {
         }
         
         self.titleLabel?.text = organismType
-        self.organismLabel?.text = "\n".join(lines)
+        self.organismLabel?.text = lines.joinWithSeparator("\n")
         self.progressView?.progress = 0
         
         self.headerContainer?.setNeedsLayout()

CoreStoreDemo/CoreStoreDemo/Transactions Demo/TransactionsDemoViewController.swift

@@ -78,7 +78,7 @@ class TransactionsDemoViewController: UIViewController, MKMapViewDelegate, Objec
         
         let alert = UIAlertController(
             title: "Transactions Demo",
-            message: "This demo shows how to use the 3 types of transactions to save updates: synchronous, asynchronous, and detached.\n\nTap and hold on the map to change the pin location.",
+            message: "This demo shows how to use the 3 types of transactions to save updates: synchronous, asynchronous, and unsafe.\n\nTap and hold on the map to change the pin location.",
             preferredStyle: .Alert
         )
         alert.addAction(UIAlertAction(title: "OK", style: .Cancel, handler: nil))
@@ -159,13 +159,14 @@ class TransactionsDemoViewController: UIViewController, MKMapViewDelegate, Objec
         
         if let mapView = self.mapView, let gesture = sender as? UILongPressGestureRecognizer where gesture.state == .Began {
             
+            let coordinate = mapView.convertPoint(
+                gesture.locationInView(mapView),
+                toCoordinateFromView: mapView
+            )
             CoreStore.beginAsynchronous { (transaction) -> Void in
                 
                 let place = transaction.edit(Static.placeController.object)
-                place?.coordinate = mapView.convertPoint(
-                    gesture.locationInView(mapView),
-                    toCoordinateFromView: mapView
-                )
+                place?.coordinate = coordinate
                 transaction.commit { (_) -> Void in }
             }
         }
@@ -183,7 +184,7 @@ class TransactionsDemoViewController: UIViewController, MKMapViewDelegate, Objec
     
     func geocodePlace(place: Place) {
         
-        let transaction = CoreStore.beginDetached()
+        let transaction = CoreStore.beginUnsafe()
         
         self.geocoder?.cancelGeocode()
         

CoreStoreTests/CoreStoreTests.swift

@@ -23,7 +23,6 @@
 //  SOFTWARE.
 //
 
-import UIKit
 import XCTest
 
 @testable
@@ -103,7 +102,7 @@ class CoreStoreTests: XCTestCase {
             XCTFail(error.description)
         }
         
-        let detachedTransaction = CoreStore.beginDetached()
+        let unsafeTransaction = CoreStore.beginUnsafe()
         
         let createExpectation = self.expectationWithDescription("Entity creation")
         CoreStore.beginAsynchronous { (transaction) -> Void in
@@ -182,7 +181,7 @@ class CoreStoreTests: XCTestCase {
                 )
                 XCTAssertNil(objs4test, "objs4test == nil")
                 
-                let objs5test = detachedTransaction.fetchCount(From(TestEntity2))
+                let objs5test = unsafeTransaction.fetchCount(From(TestEntity2))
                 XCTAssertTrue(objs5test == 3, "objs5test == 3")
                 
                 XCTAssertTrue(NSThread.isMainThread(), "NSThread.isMainThread()")
@@ -289,15 +288,15 @@ class CoreStoreTests: XCTestCase {
         XCTAssertNotNil(objs2, "objs2 != nil")
         XCTAssertTrue(objs2?.count == 1, "objs2?.count == 1")
         
-        let detachedExpectation = self.expectationWithDescription("Query creation")
+        let unsafeExpectation = self.expectationWithDescription("Query creation")
         
-        let obj5 = detachedTransaction.create(Into<TestEntity1>("Config1"))
+        let obj5 = unsafeTransaction.create(Into<TestEntity1>("Config1"))
         obj5.testEntityID = 5
         obj5.testString = "hihihi"
         obj5.testNumber = 70
         obj5.testDate = NSDate()
         
-        detachedTransaction.commit { (result) -> Void in
+        unsafeTransaction.commit { (result) -> Void in
             
             XCTAssertTrue(NSThread.isMainThread(), "NSThread.isMainThread()")
             switch result {
@@ -322,13 +321,13 @@ class CoreStoreTests: XCTestCase {
                 )
                 XCTAssertTrue(count == 1, "count == 1 (actual: \(count))")
                 
-                let obj6 = detachedTransaction.create(Into<TestEntity1>())
+                let obj6 = unsafeTransaction.create(Into<TestEntity1>())
                 obj6.testEntityID = 6
                 obj6.testString = "huehuehue"
                 obj6.testNumber = 130
                 obj6.testDate = NSDate()
                 
-                detachedTransaction.commit { (result) -> Void in
+                unsafeTransaction.commit { (result) -> Void in
                     
                     XCTAssertTrue(NSThread.isMainThread(), "NSThread.isMainThread()")
                     switch result {
@@ -358,7 +357,7 @@ class CoreStoreTests: XCTestCase {
                         )
                         XCTAssertTrue(count2 == 0, "count == 0 (actual: \(count2))")
                         
-                        detachedExpectation.fulfill()
+                        unsafeExpectation.fulfill()
                         
                     case .Failure(let error):
                         XCTFail(error.description)
@@ -377,8 +376,9 @@ class CoreStoreTests: XCTestCase {
         
         do {
             
-            try NSFileManager.defaultManager().removeItemAtURL(
-                NSFileManager.defaultManager().URLsForDirectory(.ApplicationSupportDirectory, inDomains: .UserDomainMask).first!
+            let fileManager = NSFileManager.defaultManager()
+            try fileManager.removeItemAtURL(
+                fileManager.URLsForDirectory(.ApplicationSupportDirectory, inDomains: .UserDomainMask).first!
             )
         }
         catch _ { }

CoreStoreTests/Model.xcdatamodeld/Model.xcdatamodel/contents

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<model userDefinedModelVersionIdentifier="" type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="7701" systemVersion="14D136" minimumToolsVersion="Xcode 4.3" macOSVersion="Automatic" iOSVersion="Automatic">
+<model userDefinedModelVersionIdentifier="" type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="9057" systemVersion="15B42" minimumToolsVersion="Xcode 4.3">
     <entity name="TestEntity1AAA" representedClassName="CoreStoreTests.TestEntity1" syncable="YES">
         <attribute name="testDate" optional="YES" attributeType="Date" syncable="YES"/>
         <attribute name="testEntityID" attributeType="Integer 64" syncable="YES"/>

README.md

@@ -1,11 +1,12 @@
 # CoreStore
+[![Build Status](https://travis-ci.org/JohnEstropia/CoreStore.svg)](https://travis-ci.org/JohnEstropia/CoreStore)
 [![Version](https://img.shields.io/cocoapods/v/CoreStore.svg?style=flat)](http://cocoadocs.org/docsets/CoreStore)
 [![Platform](https://img.shields.io/cocoapods/p/CoreStore.svg?style=flat)](http://cocoadocs.org/docsets/CoreStore)
 [![License](https://img.shields.io/cocoapods/l/CoreStore.svg?style=flat)](https://raw.githubusercontent.com/JohnEstropia/CoreStore/master/LICENSE)
 [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 
 Unleashing the real power of Core Data with the elegance and safety of Swift
-(Swift 2.0, iOS 8+)
+* Swift 2.1 (XCode 7.1), iOS 8+/OSX 10.10+ (or try out the [iOS 7 branch](https://github.com/JohnEstropia/CoreStore/tree/ios7_support_alpha))
 
 [Click here for a wiki version of this README](https://github.com/JohnEstropia/CoreStore/wiki)
 
@@ -14,7 +15,7 @@ Unleashing the real power of Core Data with the elegance and safety of Swift
 ## What CoreStore does better:
 
 - Heavily supports multiple persistent stores per data stack, just the way *.xcdatamodeld* files are designed to. CoreStore will also manage one data stack by default, but you can create and manage as many as you need.
-- **New in 1.0.0:** Incremental Migrations! Just tell the data stack the sequence of model versions and CoreStore will automatically use incremental migrations if needed on stores added to that stack.
+- Incremental Migrations! Just tell the data stack the sequence of model versions and CoreStore will automatically use incremental migrations if needed on stores added to that stack.
 - Ability to plug-in your own logging framework
 - Gets around a limitation with other Core Data wrappers where the entity name should be the same as the `NSManagedObject` subclass name. CoreStore loads entity-to-class mappings from the managed object model file, so you are free to name them independently.
 - Provides type-safe, easy to configure observers to replace `NSFetchedResultsController` and KVO
@@ -22,8 +23,9 @@ Unleashing the real power of Core Data with the elegance and safety of Swift
 - Makes it hard to fall into common concurrency mistakes. All `NSManagedObjectContext` tasks are encapsulated into safer, higher-level abstractions without sacrificing flexibility and customizability.
 - Exposes clean and convenient API designed around Swift’s code elegance and type safety.
 - Documentation! No magic here; all public classes, functions, properties, etc. have detailed Apple Docs. This README also introduces a lot of concepts and explains a lot of CoreStore's behavior.
+- **New in 1.3.0:** Efficient importing utilities!
 
-**CoreStore's goal is not to expose shorter, magical syntax, but to provide an API that focuses on readability, consistency, and safety.**
+**[Or vote for the next feature!](http://goo.gl/RIiHMP)**
 
 
 
@@ -40,10 +42,12 @@ Unleashing the real power of Core Data with the elegance and safety of Swift
         - [Transaction types](#transaction-types)
             - [Asynchronous transactions](#asynchronous-transactions)
             - [Synchronous transactions](#synchronous-transactions)
-            - [Detached transactions](#detached-transactions)
+            - [Unsafe transactions](#unsafe-transactions)
         - [Creating objects](#creating-objects)
         - [Updating objects](#updating-objects)
         - [Deleting objects](#deleting-objects)
+        - [Passing objects safely](#passing-objects-safely)
+    - [Importing data](#importing-data)
     - [Fetching and querying](#fetching-and-querying)
         - [`From` clause](#from-clause)
         - [Fetching](#fetching)
@@ -54,7 +58,7 @@ Unleashing the real power of Core Data with the elegance and safety of Swift
             - [`Select<T>` clause](#selectt-clause)
             - [`GroupBy` clause](#groupby-clause)
     - [Logging and error handling](#logging-and-error-handling)
-    - [Observing changes and notifications](#observing-changes-and-notifications)
+    - [Observing changes and notifications](#observing-changes-and-notifications) (unavailable on OSX)
         - [Observe a single object](#observe-a-single-object)
         - [Observe a list of objects](#observe-a-list-of-objects)
 - [Roadmap](#roadmap)
@@ -143,7 +147,7 @@ If you are already familiar with the inner workings of CoreData, here is a mappi
 | --- | --- |
 | `NSManagedObjectModel` / `NSPersistentStoreCoordinator`<br />(.xcdatamodeld file) | `DataStack` |
 | `NSPersistentStore`<br />("Configuration"s in the .xcdatamodeld file) | `DataStack` configuration<br />(multiple sqlite / in-memory stores per stack) |
-| `NSManagedObjectContext` | `BaseDataTransaction` subclasses<br />(`SynchronousDataTransaction`, `AsynchronousDataTransaction`, `DetachedDataTransaction`) |
+| `NSManagedObjectContext` | `BaseDataTransaction` subclasses<br />(`SynchronousDataTransaction`, `AsynchronousDataTransaction`, `UnsafeDataTransaction`) |
 
 Popular libraries [RestKit](https://github.com/RestKit/RestKit) and [MagicalRecord](https://github.com/magicalpanda/MagicalRecord) set up their `NSManagedObjectContext`s this way:
 
@@ -252,7 +256,7 @@ class MyViewController: UIViewController {
 
 
 ## Migrations
-So far we have only seen `addSQLiteStoreAndWait(...)` used to initialize our persistent store. As the method name's "AndWait" suffix suggests, this method will block, even if a migration occurs. If migrations are expected, the asynchronous variant `addSQLiteStore(... completion:)` method is recommended:
+So far we have only seen `addSQLiteStoreAndWait(...)` used to initialize our persistent store. As the method name's "AndWait" suffix suggests, this method blocks so it should not do long tasks such as store migrations (in fact CoreStore won't even attempt to, and any model mismatch will be reported as an error). If migrations are expected, the asynchronous variant `addSQLiteStore(... completion:)` method should be used instead:
 ```swift
 do {
     let progress: NSProgress = try dataStack.addSQLiteStore(
@@ -373,7 +377,7 @@ CoreStore.beginAsynchronous { (transaction) -> Void in
 ```
 The `commit()` method saves the changes to the persistent store. If `commit()` is not called when the transaction block completes, all changes within the transaction is discarded.
 
-The examples above use `beginAsynchronous(...)`, but there are actually 3 types of transactions at your disposal: *asynchronous*, *synchronous*, and *detached*.
+The examples above use `beginAsynchronous(...)`, but there are actually 3 types of transactions at your disposal: *asynchronous*, *synchronous*, and *unsafe*.
 
 ### Transaction types
 
@@ -399,10 +403,10 @@ CoreStore.beginSynchronous { (transaction) -> Void in
 
 Since `beginSynchronous(...)` technically blocks two queues (the caller's queue and the transaction's background queue), it is considered less safe as it's more prone to deadlock. Take special care that the closure does not block on any other external queues.
 
-#### Detached transactions
+#### Unsafe transactions
 are special in that they do not enclose updates within a closure:
 ```swift
-let transaction = CoreStore.beginDetached()
+let transaction = CoreStore.beginUnsafe()
 // make changes
 downloadJSONWithCompletion({ (json) -> Void in
 
@@ -417,7 +421,7 @@ downloadAnotherJSONWithCompletion({ (json) -> Void in
 ```
 This allows for non-contiguous updates. Do note that this flexibility comes with a price: you are now responsible for managing concurrency for the transaction. As uncle Ben said, "with great power comes great race conditions."
 
-As the above example also shows, only detached transactions are allowed to call `commit()` multiple times; doing so with synchronous and asynchronous transactions will trigger an assert. 
+As the above example also shows, only unsafe transactions are allowed to call `commit()` multiple times; doing so with synchronous and asynchronous transactions will trigger an assert. 
 
 
 You've seen how to create transactions, but we have yet to see how to make *creates*, *updates*, and *deletes*. The 3 types of transactions above are all subclasses of `BaseDataTransaction`, which implements the methods shown below.
@@ -475,7 +479,7 @@ let jane: MyPersonEntity = // ...
 CoreStore.beginAsynchronous { (transaction) -> Void in
     // WRONG: jane.age = jane.age + 1
     // RIGHT:
-    let jane = transaction.edit(jane) // using the same variable name protects us from misusing the non-transaction instance
+    let jane = transaction.edit(jane)! // using the same variable name protects us from misusing the non-transaction instance
     jane.age = jane.age + 1
     transaction.commit()
 }
@@ -488,9 +492,9 @@ let john: MyPersonEntity = // ...
 CoreStore.beginAsynchronous { (transaction) -> Void in
     // WRONG: jane.friends = [john]
     // RIGHT:
-    let jane = transaction.edit(jane)
-    let john = transaction.edit(john)
-    jane.friends = [john]
+    let jane = transaction.edit(jane)!
+    let john = transaction.edit(john)!
+    jane.friends = NSSet(array: [john])
     transaction.commit()
 }
 ```
@@ -528,6 +532,215 @@ CoreStore.beginAsynchronous { (transaction) -> Void in
 }
 ```
 
+### Passing objects safely
+
+Always remember that the `DataStack` and individual transactions manage different `NSManagedObjectContext`s so you cannot just use objects between them. That's why transactions have an `edit(...)` method:
+```swift
+let jane: MyPersonEntity = // ...
+
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let jane = transaction.edit(jane)!
+    jane.age = jane.age + 1
+    transaction.commit()
+}
+```
+But `CoreStore`, `DataStack` and `BaseDataTransaction` have a very flexible `fetchExisting(...)` method that you can pass instances back and forth with:
+```swift
+let jane: MyPersonEntity = // ...
+
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let jane = transaction.fetchExisting(jane)! // instance for transaction
+    jane.age = jane.age + 1
+    transaction.commit {
+        let jane = CoreStore.fetchExisting(jane)! // instance for DataStack
+        print(jane.age)
+    }
+}
+```
+`fetchExisting(...)` also works with multiple `NSManagedObject`s or with `NSManagedObjectID`s:
+```swift
+var peopleIDs: [NSManagedObjectID] = // ...
+
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let jane = transaction.fetchOne(
+        From(MyPersonEntity),
+        Where("name", isEqualTo: "Jane Smith")
+    )
+    jane.friends = NSSet(array: transactin.fetchExisting(peopleIDs)!)
+    // ...
+}
+```
+
+
+## Importing data
+Some times, if not most of the time, the data that we save to Core Data comes from external sources such as web servers or external files. Say you have a JSON dictionary, you may be extracting values as such:
+```swift
+let json: [String: AnyObject] = // ...
+person.name = json["name"] as? NSString
+person.age = json["age"] as? NSNumber
+// ...
+```
+If you have many attributes, you don't want to keep repeating this mapping everytime you want to import data. CoreStore lets you write the data mapping code just once, and all you have to do is call `importObject(...)` or `importUniqueObject(...)` through `BaseDataTransaction` subclasses:
+```swift
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let json: [String: AnyObject] = // ...
+    try! transaction.importObject(
+        Into(MyPersonEntity),
+        source: json
+    )
+    transaction.commit()
+}
+```
+To support data import for an entity, implement either `ImportableObject` or `ImportableUniqueObject` on the `NSManagedObject` subclass:
+- `ImportableObject`: Use this protocol if the object have no inherent uniqueness and new objects should always be added when calling `importObject(...)`.
+- `ImportableUniqueObject`: Use this protocol to specify a unique ID for an object that will be used to distinguish whether a new object should be created or if an existing object should be updated when calling `importUniqueObject(...)`.
+
+Both protocols require implementers to specify an `ImportSource` which can be set to any type that the object can extract data from:
+```swift
+typealias ImportSource = NSDictionary
+```
+```swift
+typealias ImportSource = [String: AnyObject]
+```
+```swift
+typealias ImportSource = NSData
+```
+You can even use external types from popular 3rd-party JSON libraries ([SwiftyJSON](https://github.com/SwiftyJSON/SwiftyJSON)'s `JSON` type is a personal favorite), or just simple tuples or primitives.
+
+#### `ImportableObject`
+`ImportableObject` is a very simple protocol:
+```swift
+public protocol ImportableObject: class {
+    typealias ImportSource
+    static func shouldInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool
+    func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws
+}
+```
+First, set `ImportSource` to the expected type of the data source:
+```swift
+typealias ImportSource = [String: AnyObject]
+```
+This lets us call `importObject(_:source:)` with any `[String: AnyObject]` type as the argument to `source`:
+```swift
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let json: [String: AnyObject] = // ...
+    try! transaction.importObject(
+        Into(MyPersonEntity),
+        source: json
+    )
+    // ...
+}
+```
+The actual extraction and assignment of values should be implemented in the `didInsertFromImportSource(...)` method of the `ImportableObject` protocol:
+```swift
+func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws {
+    self.name = source["name"] as? NSString
+    self.age = source["age"] as? NSNumber
+    // ...
+}
+```
+Transactions also let you import multiple objects at once using the `importObjects(_:sourceArray:)` method:
+```swift
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let jsonArray: [[String: AnyObject]] = // ...
+    try! transaction.importObjects(
+        Into(MyPersonEntity),
+        sourceArray: jsonArray
+    )
+    // ...
+}
+```
+Doing so tells the transaction to iterate through the array of import sources and calls `shouldInsertFromImportSource(...)` on the `ImportableObject` to determine which instances should be created. You can do validations and return `false` from `shouldInsertFromImportSource(...)` if you want to skip importing from a source and continue on with the other sources in the array.
+
+If on the other hand, your validation in one of the sources failed in such a manner that all other sources should also be cancelled, you can `throw` from within `didInsertFromImportSource(...)`:
+```swift
+func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws {
+    self.name = source["name"] as? NSString
+    self.age = source["age"] as? NSNumber
+    // ...
+    if self.name == nil {
+        throw Errors.InvalidNameError
+    }
+}
+```
+Doing so can let you abandon an invalid transaction immediately:
+```swift
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let jsonArray: [[String: AnyObject]] = // ...
+    do {
+        try transaction.importObjects(
+            Into(MyPersonEntity),
+            sourceArray: jsonArray
+        )
+    }
+    catch {
+        return // Woops, don't save
+    }
+    transaction.commit {
+        // ...
+    }
+}
+```
+
+#### `ImportableUniqueObject`
+Typically, we don't just keep creating objects every time we import data. Usually we also need to update already existing objects. Implementing the `ImportableUniqueObject` protocol lets you specify a "unique ID" that transactions can use to search existing objects before creating new ones:
+```swift
+public protocol ImportableUniqueObject: ImportableObject {
+    typealias ImportSource
+    typealias UniqueIDType: NSObject
+
+    static var uniqueIDKeyPath: String { get }
+    var uniqueIDValue: UniqueIDType { get set }
+
+    static func shouldInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool
+    static func shouldUpdateFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) -> Bool
+    static func uniqueIDFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws -> UniqueIDType?
+    func didInsertFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws
+    func updateFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws
+}
+```
+Notice that it has the same insert methods as `ImportableObject`, with additional methods for updates and for specifying the unique ID:
+```swift
+class var uniqueIDKeyPath: String {
+    return "personID" 
+}
+var uniqueIDValue: NSNumber { 
+    get { return self.personID }
+    set { self.personID = newValue }
+}
+class func uniqueIDFromImportSource(source: ImportSource, inTransaction transaction: BaseDataTransaction) throws -> NSNumber? {
+    return source["id"] as? NSNumber
+}
+```
+For `ImportableUniqueObject`, the extraction and assignment of values should be implemented from the `updateFromImportSource(...)` method. The `didInsertFromImportSource(...)` by default calls `updateFromImportSource(...)`, but you can separate the implementation for inserts and updates if needed.
+
+You can then call create/update an object by calling a transaction's `importUniqueObject(...)` method:
+```swift
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let json: [String: AnyObject] = // ...
+    try! transaction.importUniqueObject(
+        Into(MyPersonEntity),
+        source: json
+    )
+    // ...
+}
+```
+or multiple objects at once with the `importUniqueObjects(...)` method:
+
+```swift
+CoreStore.beginAsynchronous { (transaction) -> Void in
+    let jsonArray: [[String: AnyObject]] = // ...
+    try! transaction.importObjects(
+        Into(MyPersonEntity),
+        sourceArray: jsonArray
+    )
+    // ...
+}
+```
+As with `ImportableObject`, you can control wether to skip importing an object by implementing 
+`shouldInsertFromImportSource(...)` and `shouldUpdateFromImportSource(...)`, or to cancel all objects by `throw`ing an error from the `uniqueIDFromImportSource(...)`, `didInsertFromImportSource(...)` or `updateFromImportSource(...)` methods.
+
+
 ## Fetching and Querying
 Before we dive in, be aware that CoreStore distinguishes between *fetching* and *querying*:
 - A *fetch* executes searches from a specific *transaction* or *data stack*. This means fetches can include pending objects (i.e. before a transaction calls on `commit()`.) Use fetches when:
@@ -812,7 +1025,7 @@ Doing so channels all logging calls to your logger.
 
 Note that to keep the call stack information intact, all calls to these methods are **NOT** thread-managed. Therefore you have to make sure that your logger is thread-safe or you may otherwise have to dispatch your logging implementation to a serial queue.
 
-## Observing changes and notifications
+## Observing changes and notifications (unavailable on OSX)
 CoreStore provides type-safe wrappers for observing managed objects:
 
 - `ObjectMonitor`: use to monitor changes to a single `NSManagedObject` instance (instead of Key-Value Observing)
@@ -956,7 +1169,7 @@ let person2 = self.monitor[1, 2]
 # Installation
 - Requires:
     - iOS 8 SDK and above
-    - Swift 1.2
+    - Swift 2.0 (XCode 7 beta 6)
 - Dependencies:
     - [GCDKit](https://github.com/JohnEstropia/GCDKit)
 
@@ -968,7 +1181,8 @@ This installs CoreStore as a framework. Declare `import CoreStore` in your swift
 
 ### Install with Carthage
 ```
-github "JohnEstropia/CoreStore" >= 0.2.0
+github "JohnEstropia/CoreStore" >= 1.3.0
+github "JohnEstropia/GCDKit" >= 1.1.5
 ```
 
 ### Install as Git Submodule