为什么我的 FaceTime 群组活动彼此不同步？

如何解决为什么我的 FaceTime 群组活动彼此不同步？

我正在测试用于共享活动的新 FaceTime API。即使我跟随开发人员会议，我的数据偶尔也会不同步。我相信这可能与我在下面遇到的运行时错误有关。

“不允许从后台线程发布更改；确保在模型更新时从主线程发布值（通过如 receive(on:) 之类的操作符）。”线

开发者会话显示对 API 的发送和接收调用是异步的。

@Published var groupSession: GroupSession<DrawTogether>?
var messenger: GroupSessionMessenger?

func configureGroupSession(_ groupSession: GroupSession<DrawTogether>){
    reset()
    
    let messenger = GroupSessionMessenger(session: groupSession)
    self.messenger = messenger
    self.groupSession = groupSession
    

    groupSession.$activeParticipants
        .sink { activeParticipants in
            let newParticipants =
                activeParticipants.subtracting(groupSession.activeParticipants)
            
            async {
                do {
                    try await messenger.send(CanvasMessage(elements: self.elements),to: .only(newParticipants))
                } catch {
                    print("Unable to update new participants")
                }
            }
            
        }
        .store(in: &subscriptions)

    let emojiTask = detach { [weak self] in
        for await (message,_) in messenger.messages(of:
            UpsertEmojiMessage.self){
            await self?.handle(message)
        }
    }
    tasks.insert(emojiTask)
    
    let task = detach { [weak self] in
        for await (message,_) in messenger.messages(of: CanvasMessage.self) {
            await self?.handle(message)
        }
    }
    tasks.insert(task)
    
    groupSession.join()
}

func handle(_ message: UpsertEmojiMessage) {
    let element = Element(emoji: message.emoji,postion: message.position)
    elements.append(element)
}

func handle(_ message: CanvasMessage) {
    //guard message.elements.count > self.elements.count else { return }
    self.elements = message.elements // Warning occurs on this line
}