add "updatedItemIdentifiers" utility to ListSnapshot

CoreStore.xcodeproj/project.pbxproj

@@ -583,10 +583,10 @@
 		B5A992201EA898720091A2E3 /* UserInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5A9921E1EA898710091A2E3 /* UserInfo.swift */; };
 		B5A992211EA898720091A2E3 /* UserInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5A9921E1EA898710091A2E3 /* UserInfo.swift */; };
 		B5A992221EA898720091A2E3 /* UserInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5A9921E1EA898710091A2E3 /* UserInfo.swift */; };
-		B5AA37F1235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift */; };
+		B5AA37F1235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift */; };
-		B5AA37F2235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift */; };
+		B5AA37F2235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift */; };
-		B5AA37F3235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift */; };
+		B5AA37F3235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift */; };
-		B5AA37F4235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift */; };
+		B5AA37F4235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AA37F0235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift */; };
 		B5AA37FD235C3D1A00FFD4B9 /* SwiftUI.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B5AA37FC235C3D1A00FFD4B9 /* SwiftUI.framework */; settings = {ATTRIBUTES = (Weak, ); }; };
 		B5AEFAB51C9962AE00AD137F /* CoreStoreBridge.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AEFAB41C9962AE00AD137F /* CoreStoreBridge.swift */; };
 		B5AEFAB61C9962AE00AD137F /* CoreStoreBridge.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5AEFAB41C9962AE00AD137F /* CoreStoreBridge.swift */; };
@@ -1014,7 +1014,7 @@
 		B5A80DF52212C1BC006096AA /* Playground_iOS.playground */ = {isa = PBXFileReference; lastKnownFileType = file.playground; path = Playground_iOS.playground; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.swift; };
 		B5A991EB1E9DC2CE0091A2E3 /* VersionLock.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = VersionLock.swift; sourceTree = "<group>"; };
 		B5A9921E1EA898710091A2E3 /* UserInfo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = UserInfo.swift; sourceTree = "<group>"; };
-		B5AA37F0235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "diffableDataSource.CollectionView-AppKit.swift"; sourceTree = "<group>"; };
+		B5AA37F0235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "DiffableDataSource.CollectionView-AppKit.swift"; sourceTree = "<group>"; };
 		B5AA37FA235C3D1300FFD4B9 /* UIKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = UIKit.framework; path = Platforms/WatchOS.platform/Developer/SDKs/WatchOS6.0.sdk/System/Library/Frameworks/UIKit.framework; sourceTree = DEVELOPER_DIR; };
 		B5AA37FC235C3D1A00FFD4B9 /* SwiftUI.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SwiftUI.framework; path = Platforms/WatchOS.platform/Developer/SDKs/WatchOS6.0.sdk/System/Library/Frameworks/SwiftUI.framework; sourceTree = DEVELOPER_DIR; };
 		B5AD60CD1C90141E00F2B2E8 /* Package.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Package.swift; sourceTree = SOURCE_ROOT; };
@@ -1609,7 +1609,7 @@
 				B5BF7FB1234C97910070E741 /* DiffableDataSource.swift */,
 				B5BF7FB6234C97CE0070E741 /* DiffableDataSource.TableView-UIKit.swift */,
 				B5635D132356C39500B80E6B /* DiffableDataSource.CollectionView-UIKit.swift */,
-				B5AA37F0235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift */,
+				B5AA37F0235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift */,
 			);
 			name = DataSources;
 			sourceTree = "<group>";
@@ -2121,7 +2121,7 @@
 				B5A261211B64BFDB006EB6D3 /* MigrationType.swift in Sources */,
 				B53FBA0B1CAB5E6500F0D40A /* CSCoreStore+Migrating.swift in Sources */,
 				B5E84F141AFF847B0064E85B /* DataStack+Querying.swift in Sources */,
-				B5AA37F1235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */,
+				B5AA37F1235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */,
 				B5D7A5B61CA3BF8F005C752B /* CSInto.swift in Sources */,
 				B56007141B3F6C2800A9A8F9 /* SectionBy.swift in Sources */,
 				B5DE522B230BD7CC00A22534 /* Internals.swift in Sources */,
@@ -2474,7 +2474,7 @@
 				B52F743E1E9B8724005F3DAC /* DynamicSchema.swift in Sources */,
 				18166884232B9ED00097C275 /* KeyPath+KeyPaths.swift in Sources */,
 				B5E8A72121C1015300EF006A /* CoreStoreObject+Observing.swift in Sources */,
-				B5AA37F2235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */,
+				B5AA37F2235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */,
 				B50E175D2351848E004F033C /* Internals.DiffableDataUIDispatcher.DiffResult.swift in Sources */,
 				B5474D162227C08700B21FEC /* Internals.CoreStoreFetchRequest.swift in Sources */,
 				B501322B2346A9AE00FC238B /* ListPublisher.swift in Sources */,
@@ -2698,7 +2698,7 @@
 				B52F74401E9B8724005F3DAC /* DynamicSchema.swift in Sources */,
 				18166886232B9ED20097C275 /* KeyPath+KeyPaths.swift in Sources */,
 				B5E8A72321C1015300EF006A /* CoreStoreObject+Observing.swift in Sources */,
-				B5AA37F4235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */,
+				B5AA37F4235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */,
 				B50E175F2351848E004F033C /* Internals.DiffableDataUIDispatcher.DiffResult.swift in Sources */,
 				B5474D182227C08700B21FEC /* Internals.CoreStoreFetchRequest.swift in Sources */,
 				B501322E2346A9B100FC238B /* ListPublisher.swift in Sources */,
@@ -2922,7 +2922,7 @@
 				B52F743F1E9B8724005F3DAC /* DynamicSchema.swift in Sources */,
 				18166885232B9ED10097C275 /* KeyPath+KeyPaths.swift in Sources */,
 				B5E8A72221C1015300EF006A /* CoreStoreObject+Observing.swift in Sources */,
-				B5AA37F3235C28EE00FFD4B9 /* diffableDataSource.CollectionView-AppKit.swift in Sources */,
+				B5AA37F3235C28EE00FFD4B9 /* DiffableDataSource.CollectionView-AppKit.swift in Sources */,
 				B50E175E2351848E004F033C /* Internals.DiffableDataUIDispatcher.DiffResult.swift in Sources */,
 				B5474D172227C08700B21FEC /* Internals.CoreStoreFetchRequest.swift in Sources */,
 				B501322D2346A9B000FC238B /* ListPublisher.swift in Sources */,

Sources/Internals.DiffableDataSourceSnapshot.swift

@@ -96,6 +96,11 @@ extension Internals {
             return self.structure.allItemIDs
         }
 
+        var updatedItemIdentifiers: Set<NSManagedObjectID> {
+
+            return self.structure.reloadedItems
+        }
+
         func numberOfItems(inSection identifier: String) -> Int {
 
             return self.itemIdentifiers(inSection: identifier).count
@@ -121,16 +126,6 @@ extension Internals {
             return self.structure.allSectionIDs.firstIndex(of: identifier)
         }
 
-        func isReloaded(sectionID: String) -> Bool? {
-
-            return self.structure.isReloaded(sectionID: sectionID)
-        }
-
-        func isReloaded(itemID: NSManagedObjectID) -> Bool? {
-
-            return self.structure.isReloaded(itemID: itemID)
-        }
-
         mutating func appendItems(_ identifiers: [NSManagedObjectID], toSection sectionIdentifier: String?) {
 
             self.structure.append(itemIDs: identifiers, to: sectionIdentifier)
@@ -282,10 +277,12 @@ extension Internals {
             // MARK: Internal
 
             var sections: [Section]
+            private(set) var reloadedItems: Set<NSManagedObjectID>
 
             init() {
 
                 self.sections = []
+                self.reloadedItems = []
             }
 
             init(sections: [NSFetchedResultsSectionInfo], fetchOffset: Int, fetchLimit: Int?) {
@@ -327,6 +324,7 @@ extension Internals {
                     )
                 }
                 self.sections = newSections
+                self.reloadedItems = []
             }
 
             var allSectionIDs: [String] {
@@ -339,24 +337,6 @@ extension Internals {
                 return self.sections.lazy.flatMap({ $0.elements }).map({ $0.differenceIdentifier })
             }
 
-            func isReloaded(sectionID: String) -> Bool? {
-
-                return self.sections.first(where: { $0.differenceIdentifier == sectionID })?.isReloaded
-            }
-
-            func isReloaded(itemID: NSManagedObjectID) -> Bool? {
-
-                for section in self.sections {
-
-                    guard let item = section.elements.first(where: { $0.differenceIdentifier == itemID }) else {
-
-                        return nil
-                    }
-                    return item.isReloaded
-                }
-                return nil
-            }
-
             func items(in sectionID: String) -> [NSManagedObjectID] {
 
                 guard let sectionIndex = self.sectionIndex(of: sectionID) else {
@@ -488,6 +468,7 @@ extension Internals {
             mutating func update<S: Sequence>(itemIDs: S) where S.Element == NSManagedObjectID {
 
                 let itemPositionMap = self.itemPositionMap()
+                var newItemIDs: Set<NSManagedObjectID> = []
                 for itemID in itemIDs {
 
                     guard let itemPosition = itemPositionMap[itemID] else {
@@ -496,7 +477,9 @@ extension Internals {
                     }
                     self.sections[itemPosition.sectionIndex]
                         .elements[itemPosition.itemRelativeIndex].isReloaded = true
+                    newItemIDs.insert(itemID)
                 }
+                self.reloadedItems.formUnion(newItemIDs)
             }
 
             mutating func append(sectionIDs: [String]) {

Sources/ListSnapshot.swift

@@ -215,25 +215,11 @@ public struct ListSnapshot<O: DynamicObject>: RandomAccessCollection, Hashable {
     }
 
     /**
-     Checks if the `ListSnapshot` has changes in the specified section.
+     Returns item identifiers for updated objects. This is mainly useful for Data Source adapters such as `UICollectionViewDiffableDataSource` or `UITableViewDiffableDataSource` which work on collection diffs when reloading. Since objects with same IDs resolve as "equal" in their old and new states, adapters may need extra heuristics to determine which row items need reloading. If your row items are all observing changes from each corresponding `ObjectPublisher`, or if you are using CoreStore's built-in `DiffableDataSource`s, there is no need to inspect this property.
-
-     - parameter sectionID: the section identifier. Using an index outside the valid range will return `nil`.
-     - returns: `true` if the specified section has changes, `false` if no changes, or `nil` if the `sectionID` does not exist
      */
-    public func hasChanges(sectionID: String) -> Bool? {
+    var updatedItemIdentifiers: Set<NSManagedObjectID> {
 
-        return self.diffableSnapshot.isReloaded(sectionID: sectionID)
+        return self.diffableSnapshot.updatedItemIdentifiers
-    }
-
-    /**
-     Checks if the `ListSnapshot` has changes for the specified item.
-
-     - parameter itemID: the item identifier. Using an index outside the valid range will return `nil`.
-     - returns: `true` if the specified item has changes, `false` if no changes, or `nil` if the `itemID` does not exist
-     */
-    public func hasChanges(itemID: NSManagedObjectID) -> Bool? {
-
-        return self.diffableSnapshot.isReloaded(itemID: itemID)
     }
 
     /**