View does not re-render as new messages arrive in SwiftUI

[vojtabohm]

What did you do?

1. Created a channel:

func createDirectChannel(with userIds: Set<String>) async throws {
        let chat = try chatClient.makeDirectMessageChat(with: Array(userIds), extraData: [:])
        
        try await chat.get(watch: true)
        chatChannels[userIds] = chat
    }

2. Navigated to my custom view

struct ChatRoomView: View {
    
    let chat: Chat
    init(userIds: Set<String>) {
        chat = try! ChatService.shared.getDirectChannel(for: userIds)
    }
    ...
}

(the method for getting the channel (btw. why is there no get method for a channel in the state layer?)):

func getDirectChannel(for userIds: Set<String>) throws -> Chat {
        // Retrieve the chat from the dictionary
        if let chat = chatChannels[userIds] {
            return chat
        } else {
            throw ChatError.channelCreationFailed // or handle the error as needed
        }
    }

3. Render the messages in ChatRoomView:

ForEach(chat.state.messages, id: \.id) {
                        Text($0.text)
                    }

What did you expect to happen?

The list re-renders as new messages arrive.

What happened instead?

The messages are not re-rendered. Even though they are marked as @Published (@Published public internal(set) var messages = StreamCollection<ChatMessage>([])) in the ChatState.swift file @MainActor public final class ChatState: ObservableObject

I also checked that the messages are received, both on the channel by subscribing to events and by placing a breakpoint on the internal observer the ChatState creates (line 207) messagesDidChange: { [weak self] in self?.messages = $0 }. I can confirm all events are received.

GetStream Environment

GetStream Chat version: 4.67.0
GetStream Chat frameworks: None, custom UI
iOS version: 18.0
Swift version: 5.9
Xcode version: 16.1
Device: iPhone 13 mini, iPhone 16 Pro (Simulator)

Additional context

I am aware the documentation available uses Combine but that is outdated and ugly. The @Published property hints that the view should automatically re-render, which would be awesome.

Could anyone point me to what I am doing wrong?

[vojtabohm]

I realised my mistake. You need to have a @StateObject like this, otherwise the @Published won't work:

@StateObject private var chatState: ChatState

init(userIds: Set<String>) {
        let chat = try! ChatService.shared.getDirectChannel(for: userIds)
        _chatState = StateObject(wrappedValue: chat.state)
    }