SwiftUI NSManagedObject更改不会更新视图

在我的视图模型中，如果我更新NSManagedObject属性，那么视图将不再更新。我已经附上了代码和视图模型

我在打断视图更新的行前面添加了一条注释

class StudySessionCounterViewModel: ObservableObject {

    fileprivate var studySession: StudySession

    init(_ studySession: StudySession) {
        self.studySession = studySession
    }

    @Published var elapsedTime = 14 * 60
    @Published var circleProgress: Double = 0

    var timer: Timer?

    var formattedTime: String {
        get {
            let timeToFormat = (Int(studySession.studyTime) * 60) - elapsedTime
            let minutes = timeToFormat / 60 % 60
            let seconds = timeToFormat % 60
            return String(format:"%02i:%02i", minutes, seconds)
        }
    }

    func startTimer() {
        self.timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.timerTicked), userInfo: nil, repeats: true)
        studySession.isActive = true //Adding this stops my view from updating

    }

    @objc func timerTicked() {
        elapsedTime += 1
        circleProgress = (Double(elapsedTime) / Double(studySession.studyTime * 60))
    }

    func stop() {
        timer?.invalidate()
    }

}

这是使用该视图模型的视图。添加该行时，表示格式化时间的文本不再更改，进度循环的进度保持不变。 如果我删除该行，所有内容都会更新并按预期工作

struct StudySessionCounterView: View {

    @Environment(\.presentationMode) var presentationMode

    @ObservedObject var studySessionCounterVM: StudySessionCounterViewModel

    var studySession: StudySession

    init(_ studySession: StudySession) {
        studySessionCounterVM = StudySessionCounterViewModel(studySession)
        self.studySession = studySession
    }

    @State var showAlert = false
    @State var isCounting = false

    var body: some View {

        VStack {
            ZStack {
                Text(studySessionCounterVM.formattedTime)
                    .font(.largeTitle)
                ProgressRingView(size: .large, progress: $studySessionCounterVM.circleProgress)
            }

            Spacer()

            if isCounting {
                Button(action: {
                    self.studySessionCounterVM.stop()
                    self.isCounting = false
                }) {
                    Image(systemName: "stop.circle")
                        .resizable()
                        .frame(width: 64, height: 64, alignment: .center)
                        .foregroundColor(.orange)
                }
            } else {
                Button(action: {
                    self.studySessionCounterVM.startTimer()
                    self.isCounting = true
                }) {
                    Image(systemName: "play.circle")
                        .resizable()
                        .frame(width: 64, height: 64, alignment: .center)
                        .foregroundColor(.orange)
                }
            }

        }.padding()
            .navigationBarTitle("Matematica", displayMode: .inline)
    }
}

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更新：发现每次NSManagedObject更改属性时，视图模型都会重新初始化。仍然没有解决方案，不幸的是

您找到解决方案了吗？有同样的问题。。。