为什么 scenePhase 值是 .background 而应用程序在前台？

Question

我想在应用程序进入后台时从模型文件中执行某些操作，例如停止计时器或其他操作。但是当我运行应用程序并检查 scenePhase 值时它 returns .background 而应用程序在前台。

import SwiftUI
import Combine

class Model {
    @Environment(\.scenePhase) var scenePhase
    var timerSubscription: AnyCancellable?
    init() {
        timerSubscription = Timer.publish(every: 1, on: .main, in: .common).autoconnect().sink { _ in
            if self.scenePhase == .background {
                // do something when the app goes to the background.
            }
            print(self.scenePhase) // print background while the app is in the foreground.
        }
    }
}

struct ContentView: View {
    var model = Model()
    var body: some View {
        Text("Hello, world!")
            .padding()
            
    }
}

Answer 1

仔细阅读第一句到最后：

更新：

what do you suggest to achieve the logic I described in the model file?

将环境移动到视图，它应该在的位置，并在视图拥有它或检测到它的变化时将其重新注入模型，例如

class Model {
    var scenePhase: ScenePhase?
    var timerSubscription: AnyCancellable?
    init() {
        timerSubscription = Timer.publish(every: 1, on: .main, in: .common).autoconnect().sink { _ in
            if self.scenePhase == .background {
                // do something when the app goes to the background.
            }
            print(self.scenePhase ?? .none) // print background while the app is in the foreground.
        }
    }
}

struct ContentView: View {
    @Environment(\.scenePhase) var scenePhase  // << here !!
    var model = Model()

    var body: some View {
        Text("Hello, world!")
            .padding()
            .onChange(of: scenePhase) {
               self.model.scenePhase = [=10=]  // << update !!
            }
            .onAppear {
               self.model.scenePhase = scenePhase  // << initial !!
            }
    }
}

为什么 scenePhase 值是 .background 而应用程序在前台？

Why scenePhase value is .background while the app is in the foreground?

swift

swiftui

combine