当使用合并观察Singleton中的变化时，变化似乎无法识别。我曾尝试将Singleton设置为@ObservableObject并添加self?.objectWillChange.send()，但除此之外，我不知道该怎么做。
This problem看起来很相似，但是我已经在做解决方案建议的事情了。
在我的理解中，这应该每隔3秒在“MODDED”之后打印“CHECK”，但只打印“MODDED”：

class MREViewModel: ObservableObject {
    
    private var cancellables = Set<AnyCancellable>()
    
    @Published var ownUser: MREUser
    
    init() {
        ownUser = MREUserService.shared.ownUser
        setupBindings()
    }
    
    func setupBindings() {
        MREUserService.shared.$ownUser
            .receive(on: DispatchQueue.main)
            .sink { [weak self] user in
                print("CHECK")
                self?.objectWillChange.send()
                self?.ownUser = user
            }
            .store(in: &cancellables)
    }
}

// doesn't work with or without this view that will eventually be used
struct ViewSwiftUI: View {
    
    @ObservedObject var viewModel: MREViewModel
    
    var body: some View {
        Text(viewModel.ownUser.userName)
    }
}

class MREUserService: ObservableObject {
    
    static var shared: MREUserService = MREUserService()
    
    @Published var ownUser = MREUser(userName: "initialised")
    
    var timer: Timer?
    
    init() {
        timer = Timer.scheduledTimer(withTimeInterval: 3.0, repeats: true) { timer in
            self.objectWillChange.send()
            self.ownUser.userName = "\(Date())"
            print("MODDED: \(self.ownUser.userName)")
        }
    }
}

class MREUser {
    var _id = UUID().uuidString
    var userName: String
    
    init(userName: String) {
        self.userName = userName
    }
}