Keep new messages separator visible when the channel is open (#846)

Author: laevandus

CHANGELOG.md

@@ -10,6 +10,7 @@ _June 03, 2025_
 
 ### 🐞 Fixed
 - Fix `ChatChannelView` keyboard background not using color from palette [#845](https://github.com/GetStream/stream-chat-swiftui/pull/845)
+- Fix removing new messages separator when scrolling in the channel view [#846](https://github.com/GetStream/stream-chat-swiftui/pull/846)
 
 # [4.79.0](https://github.com/GetStream/stream-chat-swiftui/releases/tag/4.79.0)
 _May 29, 2025_

Sources/StreamChatSwiftUI/ChatChannel/ChatChannelViewModel.swift

@@ -50,7 +50,7 @@ open class ChatChannelViewModel: ObservableObject, MessagesDataSource {
     private var channelName = ""
     private var onlineIndicatorShown = false
     private var lastReadMessageId: String?
-    private let throttler = Throttler(interval: 3, broadcastLatestEvent: true)
+    var throttler = Throttler(interval: 3, broadcastLatestEvent: true)
 
     public var channelController: ChatChannelController
     public var messageController: ChatMessageController?
@@ -574,9 +574,7 @@ open class ChatChannelViewModel: ObservableObject, MessagesDataSource {
         guard let channel, channel.unreadCount.messages > 0 else { return }
         throttler.throttle { [weak self] in
             self?.channelController.markRead()
-            DispatchQueue.main.async {
-                self?.firstUnreadMessageId = nil
-            }
+            // We keep `firstUnreadMessageId` value set which keeps showing the new messages header in the channel view
         }
     }
 

StreamChatSwiftUITests/Tests/ChatChannel/ChatChannelViewModel_Tests.swift

@@ -553,6 +553,25 @@ class ChatChannelViewModel_Tests: StreamChatTestCase {
         // Then
         XCTAssertEqual(3, viewModel.messages.count)
     }
+    
+    func test_chatChannelVM_keepFirstUnreadIndexSetAfterMarkingTheChannelAsRead() {
+        // Given
+        let message1 = ChatMessage.mock()
+        let message2 = ChatMessage.mock()
+        let message3 = ChatMessage.mock()
+        let channelController = makeChannelController(messages: [message1, message2, message3])
+        channelController.channel_mock = .mock(cid: .unique, unreadCount: ChannelUnreadCount(messages: 1, mentions: 0))
+        let viewModel = ChatChannelViewModel(channelController: channelController)
+        viewModel.firstUnreadMessageId = message1.id
+        viewModel.throttler = Throttler_Mock(interval: 0)
+        
+        // When
+        viewModel.handleMessageAppear(index: 0, scrollDirection: .down)
+        
+        // Then
+        XCTAssertEqual(1, channelController.markReadCallCount)
+        XCTAssertNotNil(viewModel.firstUnreadMessageId)
+    }
 
     // MARK: - private
 
@@ -565,3 +584,9 @@ class ChatChannelViewModel_Tests: StreamChatTestCase {
         )
     }
 }
+
+private class Throttler_Mock: Throttler {
+    override func throttle(_ action: @escaping () -> Void) {
+        action()
+    }
+}