add batch updates

Author: imkdir

Ark.xcodeproj/project.pbxproj

@@ -27,6 +27,7 @@
 		B42875CA24EE7A7700933413 /* Ark.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B4256DC224ED1715000DF13C /* Ark.framework */; };
 		B42875CB24EE7A7700933413 /* Ark.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = B4256DC224ED1715000DF13C /* Ark.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		B44FACDA24FE2B4D0027D5A5 /* AnyNodable.swift in Sources */ = {isa = PBXBuildFile; fileRef = B44FACD924FE2B4D0027D5A5 /* AnyNodable.swift */; };
+		B44FACDC24FE5CAE0027D5A5 /* BatchUpdates.swift in Sources */ = {isa = PBXBuildFile; fileRef = B44FACDB24FE5CAE0027D5A5 /* BatchUpdates.swift */; };
 		B4E5581B24FCA9DA004C2477 /* DateFormat.swift in Sources */ = {isa = PBXBuildFile; fileRef = A6E81FA224F7A8C600AAE8B0 /* DateFormat.swift */; };
 		B4E5581E24FCC530004C2477 /* NodeEvent.swift in Sources */ = {isa = PBXBuildFile; fileRef = B4E5581D24FCC530004C2477 /* NodeEvent.swift */; };
 /* End PBXBuildFile section */
@@ -92,6 +93,7 @@
 		B42875C024EE138100933413 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		B42875C524EE2CBB00933413 /* DiffableDataSource.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DiffableDataSource.swift; sourceTree = "<group>"; };
 		B44FACD924FE2B4D0027D5A5 /* AnyNodable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AnyNodable.swift; sourceTree = "<group>"; };
+		B44FACDB24FE5CAE0027D5A5 /* BatchUpdates.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BatchUpdates.swift; sourceTree = "<group>"; };
 		B4E5581D24FCC530004C2477 /* NodeEvent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NodeEvent.swift; sourceTree = "<group>"; };
 		F0C766C3C5A77FD675545DA9 /* Pods_ArkDemo.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_ArkDemo.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		F61531B872BE69FE4C5901BD /* Pods-Ark.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Ark.release.xcconfig"; path = "Target Support Files/Pods-Ark/Pods-Ark.release.xcconfig"; sourceTree = "<group>"; };
@@ -158,6 +160,7 @@
 			children = (
 				B4256DC524ED1715000DF13C /* Ark.h */,
 				B42875AA24EE10ED00933413 /* ListDiff.swift */,
+				B44FACDB24FE5CAE0027D5A5 /* BatchUpdates.swift */,
 				B42875C524EE2CBB00933413 /* DiffableDataSource.swift */,
 				A64FD07724F681CF00EB0D38 /* Nodable.swift */,
 				B44FACD924FE2B4D0027D5A5 /* AnyNodable.swift */,
@@ -399,6 +402,7 @@
 			files = (
 				B4E5581E24FCC530004C2477 /* NodeEvent.swift in Sources */,
 				B42875AB24EE10ED00933413 /* ListDiff.swift in Sources */,
+				B44FACDC24FE5CAE0027D5A5 /* BatchUpdates.swift in Sources */,
 				A6E81FA624F7E99E00AAE8B0 /* NodeContext.swift in Sources */,
 				B42875C624EE2CBB00933413 /* DiffableDataSource.swift in Sources */,
 				B44FACDA24FE2B4D0027D5A5 /* AnyNodable.swift in Sources */,

Ark/BatchUpdates.swift

@@ -0,0 +1,36 @@
+//
+//  BatchUpdates.swift
+//  Ark
+//
+//  Created by Dwight CHENG on 2020/9/1.
+//  Copyright © 2020 Glow. All rights reserved.
+//
+
+import Foundation
+
+struct BatchUpdates {
+    var itemInserts: [IndexPath] = []
+    var itemDeletes: [IndexPath] = []
+    var itemMoves: [MoveIndexPath] = []
+}
+
+struct MoveIndexPath {
+    let from: IndexPath
+    let to: IndexPath
+}
+
+extension IndexSet {
+    func toIndexPaths(section: Int) -> [IndexPath] {
+        map({ IndexPath(item: $0, section: section) })
+    }
+}
+
+extension Array where Element == List.MoveIndex {
+    func toIndexPaths(section: Int) -> [MoveIndexPath] {
+        map({
+            MoveIndexPath(
+                from: IndexPath(item: $0.from, section: section),
+                to: IndexPath(item: $0.to, section: section))
+        })
+    }
+}

Ark/DiffableDataSource.swift

@@ -69,9 +69,31 @@ public class DiffableDataSource<Target: SectionInflator>: NSObject,
             return
         }
         self.snapshot = snapshot
-        let result = List.diffing(oldArray: oldSnapshot.sections, newArray: snapshot.sections).forBatchUpdates()
+        let result = List.diffing(oldArray: oldSnapshot.sections, newArray: snapshot.sections)
         print(result)
+        
+        func createBactchUpdates(from updates: IndexSet) -> BatchUpdates {
+            var result = BatchUpdates()
+            for section in updates {
+                let oldItems = oldSnapshot.sections[section].items
+                let newItems = snapshot.sections[section].items
+                let diffResult = List.diffing(oldArray: oldItems, newArray: newItems).forBatchUpdates()
+                result.itemDeletes += diffResult.deletes.toIndexPaths(section: section)
+                result.itemInserts += diffResult.inserts.toIndexPaths(section: section)
+                result.itemMoves += diffResult.moves.toIndexPaths(section: section)
+            }
+            return result
+        }
+        let batchUpdates = createBactchUpdates(from: result.updates)
+        
         collectionNode.performBatch(animated: animatingDifferences, updates: { [node = self.collectionNode] in
+            
+            node?.deleteItems(at: batchUpdates.itemDeletes)
+            node?.insertItems(at: batchUpdates.itemInserts)
+            
+            for move in batchUpdates.itemMoves {
+                node?.moveItem(at: move.from, to: move.to)
+            }
 
             for move in result.moves {
                 node?.moveSection(move.from, toSection: move.to)

ArkDemo/ViewController.swift

@@ -85,27 +85,19 @@ final class ViewController: ASDKViewController<ASCollectionNode> {
     }
 
     private func handleArticleEvent(_ event: GenericNodeEvent<ArticleFeed.Subject>) {
-        func findSectionAndIndex(of subject: ArticleFeed.Subject) -> (ArticleFeed, IndexPath)? {
-            for (section, model) in self.sections.enumerated() {
-                guard case .articleFeed(let feed) = model,
-                    let index = feed.subjects.firstIndex(of: subject) else {
-                    continue
-                }
-                return (feed, IndexPath(item: index, section: section))
-            }
-            return nil
+        guard case .articleFeed(let feed) = sections[event.indexPath.section],
+            let index = feed.subjects.firstIndex(of: event.model) else {
+            return
         }
-        if let (feed, indexPath) = findSectionAndIndex(of: event.model) {
-            switch event.model {
-            case .article(var article):
-                article.read.toggle()
-                var subjects = feed.subjects
-                subjects[indexPath.item] = .article(article)
-                let newFeed = HomeFeed.articleFeed(.init(date: feed.date, subjects: subjects))
-                sections[indexPath.section] = newFeed
-            case .poll(let poll):
-                break
-            }
+        switch event.model {
+        case .article(var article):
+            var subjects = feed.subjects
+            article.read.toggle()
+            subjects[index] = .article(article)
+            let newFeed = HomeFeed.articleFeed(.init(date: feed.date, subjects: subjects))
+            sections[event.indexPath.section] = newFeed
+        case .poll(let poll):
+            break
         }
     }