dual snapshot animation

apps/ios/Shared/Model/ChatModel.swift

@@ -450,13 +450,14 @@ final class ChatModel: ObservableObject {
             }
             return false
         } else {
-            var ci = cItem
-            if let status = chatItemStatuses.removeValue(forKey: ci.id), case .sndNew = ci.meta.itemStatus {
-                ci.meta.itemStatus = status
+            withConditionalAnimation(itemAnimation()) {
+                var ci = cItem
+                if let status = chatItemStatuses.removeValue(forKey: ci.id), case .sndNew = ci.meta.itemStatus {
+                    ci.meta.itemStatus = status
+                }
+                im.reversedChatItems.insert(ci, at: hasLiveDummy ? 1 : 0)
+                im.itemAdded = true
             }
-            if itemAnimation() != nil { FadeInChatItem.items.insert(ci.id) }
-            im.reversedChatItems.insert(ci, at: hasLiveDummy ? 1 : 0)
-            im.itemAdded = true
             return true
         }
 

apps/ios/Shared/Views/Chat/ChatView.swift

@@ -413,7 +413,6 @@ struct ChatView: View {
                     revealedChatItem: $revealedChatItem,
                     selectedChatItems: $selectedChatItems
                 )
-                .modifier(FadeInChatItem(id: ci.id))
                 .onAppear {
                     floatingButtonModel.appeared(viewId: ci.viewId)
                 }
@@ -1551,28 +1550,6 @@ private func buildTheme() -> AppTheme {
     }
 }
 
-struct FadeInChatItem: ViewModifier {
-    static var items = Set<ChatItem.ID>()
-    private let chatItemId: ChatItem.ID
-    @State private var isVisible: Bool
-
-    init(id: ChatItem.ID) {
-        chatItemId = id
-        isVisible = !Self.items.contains(chatItemId)
-    }
-
-    func body(content: Content) -> some View {
-        content
-            .opacity(isVisible ? 1 : 0)
-            .onAppear {
-                if !isVisible {
-                    Self.items.remove(chatItemId)
-                    withAnimation(.easeInOut(duration: 0.5)) { isVisible = true }
-                }
-            }
-    }
-}
-
 struct ToggleNtfsButton: View {
     @ObservedObject var chat: Chat
 

apps/ios/Shared/Views/Chat/ReverseList.swift

@@ -171,17 +171,32 @@ struct ReverseList<Item: Identifiable & Hashable & Sendable, Content: View>: UIV
             Task { representer.scrollState = .atDestination }
         }
 
-        func update(items: Array<Item>) {
+        var updateInProgress = false
+
+        func update(items: [Item]) {
+            if updateInProgress { return }
+            let itemsAdded = items.count - itemCount
+            if itemsAdded > 0, itemCount != 0 {
+                updateInProgress = true
+                _update(items: Array(items[1...]), animated: false) {
+                    DispatchQueue.main.async {
+                        self._update(items: items, animated: true) {
+                            self.updateInProgress = false
+                        }
+                    }
+                }
+            } else {
+               _update(items: items, animated: false)
+            }
+            itemCount = items.count
+        }
+
+        func _update(items: Array<Item>, animated: Bool, completion: (() -> Void)? = nil) {
             var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
             snapshot.appendSections([.main])
             snapshot.appendItems(items)
-            dataSource.defaultRowAnimation = .none
-            let countChange = abs(items.count - itemCount)
-            dataSource.apply(snapshot, animatingDifferences:
-                countChange > 0 && // Avoid animating initial load
-                countChange < 5    // Avoid animating page loads
-            )
-            itemCount = items.count
+            dataSource.defaultRowAnimation = animated ? .top : .none
+            dataSource.apply(snapshot, animatingDifferences: animated, completion: completion)
         }
     }