[CIS-2084] Fix message list jumps by removing the inverted table view

DemoApp/DemoAppConfiguration.swift

@@ -32,7 +32,6 @@ enum DemoAppConfiguration {
 
         configureAtlantisIfNeeded()
         trackPerformanceIfNeeded()
-        enableMessageDiffingIfNeeded()
     }
 
     // HTTP and WebSocket Proxy with Proxyman.app
@@ -51,9 +50,4 @@ enum DemoAppConfiguration {
             PerformanceMonitor.shared().start()
         }
     }
-
-    // Enable message diffing in Message List
-    private static func enableMessageDiffingIfNeeded() {
-        StreamChatWrapper.shared.setMessageDiffingEnabled(isStreamInternalConfiguration)
-    }
 }

DemoApp/StreamChat/StreamChatWrapper.swift

@@ -163,11 +163,3 @@ extension StreamChatWrapper {
         try? ChatPushNotificationInfo(content: response.notification.request.content)
     }
 }
-
-// MARK: Develop configuration
-
-extension StreamChatWrapper {
-    func setMessageDiffingEnabled(_ isEnabled: Bool) {
-        Components.default._messageListDiffingEnabled = isEnabled
-    }
-}

Sources/StreamChat/Controllers/ChannelController/ChannelController.swift

@@ -350,7 +350,7 @@ public class ChatChannelController: DataController, DelegateCallable, DataStoreP
                 return nil
             }
             guard let cid = self.cid else { return nil }
-            let sortAscending = self.messageOrdering == .topToBottom ? false : true
+            let sortAscending = self.messageOrdering == .topToBottom ? true : false
             var deletedMessageVisibility: ChatClientConfig.DeletedMessageVisibility?
             var shouldShowShadowedMessages: Bool?
             self.client.databaseContainer.viewContext.performAndWait { [weak self] in
@@ -731,7 +731,7 @@ public extension ChatChannelController {
             return
         }
 
-        guard let messageId = messageId ?? messages.last?.id else {
+        guard let messageId = messageId ?? messages.first?.id else {
             log.error(ClientError.ChannelEmptyMessages().localizedDescription)
             callback { completion?(ClientError.ChannelEmptyMessages()) }
             return

Sources/StreamChat/Controllers/MessageController/MessageController.swift

@@ -601,7 +601,7 @@ private extension ChatMessageController {
                 return nil
             }
 
-            let sortAscending = self.listOrdering == .topToBottom ? false : true
+            let sortAscending = self.listOrdering == .topToBottom ? true : false
             let deletedMessageVisibility = self.client.databaseContainer.viewContext
                 .deletedMessagesVisibility ?? .visibleForCurrentUser
             let shouldShowShadowedMessages = self.client.databaseContainer.viewContext.shouldShowShadowedMessages ?? false

Sources/StreamChatUI/ChatChannel/ChatChannelVC.swift

@@ -148,6 +148,23 @@ open class ChatChannelVC: _ViewController,
         keyboardHandler.stop()
     }
 
+    /// Handles loading the previous messages.
+    open func loadPreviousMessages() {
+        guard channelController.state == .remoteDataFetched else {
+            return
+        }
+        guard !isLoadingPreviousMessages else {
+            return
+        }
+        isLoadingPreviousMessages = true
+
+        messageListVC.showLoadingPreviousMessagesView()
+        channelController.loadPreviousMessages { [weak self] _ in
+            self?.isLoadingPreviousMessages = false
+            self?.messageListVC.hideLoadingPreviousMessagesView()
+        }
+    }
+
     // MARK: - ChatMessageListVCDataSource
 
     public var messages: [ChatMessage] {
@@ -186,26 +203,7 @@ open class ChatChannelVC: _ViewController,
         _ vc: ChatMessageListVC,
         willDisplayMessageAt indexPath: IndexPath
     ) {
-        if channelController.state != .remoteDataFetched {
-            return
-        }
-
-        guard messageListVC.listView.isTrackingOrDecelerating else {
-            return
-        }
-
-        if indexPath.row < channelController.messages.count - 10 {
-            return
-        }
-
-        guard !isLoadingPreviousMessages else {
-            return
-        }
-        isLoadingPreviousMessages = true
-
-        channelController.loadPreviousMessages { [weak self] _ in
-            self?.isLoadingPreviousMessages = false
-        }
+        // No-op
     }
 
     open func chatMessageListVC(
@@ -247,6 +245,10 @@ open class ChatChannelVC: _ViewController,
         messageComposerVC.dismissSuggestions()
     }
 
+    open func chatMessageListVCShouldLoadPreviousMessages(_ vc: ChatMessageListVC) {
+        loadPreviousMessages()
+    }
+
     // MARK: - ChatChannelControllerDelegate
 
     open func channelController(

Sources/StreamChatUI/ChatChannel/StreamModalTransitioningDelegate.swift

@@ -5,10 +5,6 @@
 import UIKit
 
 /// Stream's custom transitioning delegate to handle a modal presentation.
-///
-/// This should be used if you are presenting the ``ChatChannelVC`` in a modal.
-/// The reason this custom transition should be used instead of the native one is because we use an inverted
-/// `UITableView` for the message list component which it doesn't play well with the native modal transition.
 open class StreamModalTransitioningDelegate: NSObject, UIViewControllerTransitioningDelegate {
     public func presentationController(
         forPresented presented: UIViewController,

Sources/StreamChatUI/ChatMessageList/ChatMessage/ChatMessageLayoutOptionsResolver.swift

@@ -159,9 +159,9 @@ open class ChatMessageLayoutOptionsResolver {
         }
 
         // The current message is the last message so it's either a standalone or last in sequence.
-        guard messageIndexPath.item > 0 else { return true }
+        guard messageIndexPath.item < messages.count - 1 else { return true }
 
-        let nextMessageIndex = messages.index(before: messageIndex)
+        let nextMessageIndex = messages.index(after: messageIndex)
         guard let nextMessage = messages[safe: nextMessageIndex] else {
             indexNotFoundAssertion()
             return true

Sources/StreamChatUI/ChatMessageList/ChatMessageListScrollOverlayView.swift

@@ -48,9 +48,6 @@ open class ChatMessageListScrollOverlayView: _View, ThemeProvider {
                 else { return }
 
                 let overlayText = self.dataSource?.scrollOverlay(self, textForItemAt: indexPath)
-
-                // If we have no date we have no reason to display `dateView`
-                self.isHidden = (overlayText ?? "").isEmpty
                 self.content = overlayText
 
                 // Apple's naming is quite weird as actually this property should rather be named `isScrolling`
@@ -63,6 +60,15 @@ open class ChatMessageListScrollOverlayView: _View, ThemeProvider {
                 // that reacts on `panGestureRecognizer` states and can handle this case properly
                 if !tb.isDragging {
                     self.setAlpha(0)
+                } else {
+                    self.setAlpha(1)
+                }
+
+                /// If the date separators are enabled per cell, don't show the overlay
+                /// for the the top cell since the top cell has always a list date separator.
+                let isDateSeparatorEnabled = self.components.messageListDateSeparatorEnabled
+                if isDateSeparatorEnabled, refPointInListView.y < tb.rectForRow(at: indexPath).height {
+                    self.setAlpha(0)
                 }
             }
 
@@ -105,6 +111,7 @@ open class ChatMessageListScrollOverlayView: _View, ThemeProvider {
     open func setAlpha(_ alpha: CGFloat) {
         Animate(isAnimated: true) {
             self.alpha = alpha
+            self.isHidden = alpha == 0
         }
     }
 }