ios: optimise mark-as-read performance (#4434)

* ios: optimise mark-as-read rendering performance

* merge master

* minor

* make chat observable

* make model EnvironmentObject

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

apps/ios/Shared/Model/ChatModel.swift

@@ -74,6 +74,7 @@ final class ChatModel: ObservableObject {
     @Published var chatToTop: String?
     @Published var groupMembers: [GMember] = []
     @Published var groupMembersIndexes: Dictionary<Int64, Int> = [:] // groupMemberId to index in groupMembers list
+    @Published var membersLoaded = false
     // items in the terminal view
     @Published var showingTerminal = false
     @Published var terminalItems: [TerminalItem] = []
@@ -195,6 +196,18 @@ final class ChatModel: ObservableObject {
         return nil
     }
 
+    func loadGroupMembers(_ groupInfo: GroupInfo, updateView: @escaping () -> Void = {}) async {
+        let groupMembers = await apiListMembers(groupInfo.groupId)
+        await MainActor.run {
+            if chatId == groupInfo.id {
+                self.groupMembers = groupMembers.map { GMember.init($0) }
+                self.populateGroupMembersIndexes()
+                self.membersLoaded = true
+                updateView()
+            }
+        }
+    }
+
     private func getChatIndex(_ id: String) -> Int? {
         chats.firstIndex(where: { $0.id == id })
     }
@@ -390,8 +403,8 @@ final class ChatModel: ObservableObject {
     }
 
     func removeChatItem(_ cInfo: ChatInfo, _ cItem: ChatItem) {
-        if cItem.isRcvNew {
-            decreaseUnreadCounter(cInfo)
+        if cItem.isRcvNew, let chatIndex = getChatIndex(cInfo.id) {
+            decreaseUnreadCounter(chatIndex)
         }
         // update previews
         if let chat = getChat(cInfo.id) {
@@ -536,13 +549,18 @@ final class ChatModel: ObservableObject {
         }
     }
 
-    func markChatItemRead(_ cInfo: ChatInfo, _ cItem: ChatItem) {
-        if chatId == cInfo.id, let i = getChatItemIndex(cItem) {
-            if reversedChatItems[i].isRcvNew {
-                // update current chat
-                markChatItemRead_(i)
-                // update preview
-                decreaseUnreadCounter(cInfo)
+    func markChatItemRead(_ cInfo: ChatInfo, _ cItem: ChatItem) async {
+        if chatId == cInfo.id,
+           let itemIndex = getChatItemIndex(cItem),
+           let chatIndex = getChatIndex(cInfo.id),
+           reversedChatItems[itemIndex].isRcvNew {
+            await MainActor.run {
+                withTransaction(Transaction()) {
+                    // update current chat
+                    markChatItemRead_(itemIndex)
+                    // update preview
+                    decreaseUnreadCounter(chatIndex)
+                }
             }
         }
     }
@@ -558,11 +576,9 @@ final class ChatModel: ObservableObject {
         }
     }
 
-    func decreaseUnreadCounter(_ cInfo: ChatInfo) {
-        if let i = getChatIndex(cInfo.id) {
-            chats[i].chatStats.unreadCount = chats[i].chatStats.unreadCount - 1
-            decreaseUnreadCounter(user: currentUser!)
-        }
+    func decreaseUnreadCounter(_ chatIndex: Int) {
+        chats[chatIndex].chatStats.unreadCount = chats[chatIndex].chatStats.unreadCount - 1
+        decreaseUnreadCounter(user: currentUser!)
     }
 
     func increaseUnreadCounter(user: any UserLike) {

apps/ios/Shared/Model/SimpleXAPI.swift

@@ -1207,7 +1207,7 @@ func apiMarkChatItemRead(_ cInfo: ChatInfo, _ cItem: ChatItem) async {
     do {
         logger.debug("apiMarkChatItemRead: \(cItem.id)")
         try await apiChatRead(type: cInfo.chatType, id: cInfo.apiId, itemRange: (cItem.id, cItem.id))
-        await MainActor.run { ChatModel.shared.markChatItemRead(cInfo, cItem) }
+        await ChatModel.shared.markChatItemRead(cInfo, cItem)
     } catch {
         logger.error("apiMarkChatItemRead apiChatRead error: \(responseError(error))")
     }