swiftui - 不接收场景相位变化

Question

我正在尝试执行一些我之前放在我的应用程序委托(delegate)中的代码，例如在进入后台时保存我的托管对象上下文。我把电话拨到 .onChange对于场景阶段，但我什么也没得到。这是一个示例项目:

import SwiftUI

@main
struct PhaseApp: App {
    @Environment(\.scenePhase) private var scenePhase
    
    var body: some Scene {
        WindowGroup {
            Text("Hello, world.")
        }
        .onChange(of: scenePhase) { phase in
            switch phase {
            case .active:
                print("Active")
            case .background:
                print("Background")
            case .inactive:
                print("Inactive")
            @unknown default: break
            }
        }
    }
}

每当我按主页或点击应用程序时，我希望在模拟器或我的测试设备上获得打印命令，但没有任何 react 。

Answer 1

使用内部场景 Root View (通常为 ContentView )
使用 Xcode 12/iOS 14 进行测试。

struct ContentView: View {
    @Environment(\.scenePhase) private var scenePhase
    var body: some View {
        TestView()
            .onChange(of: scenePhase) { phase in
                switch phase {
                    case .active:
                        print(">> your code is here on scene become active")
                    case .inactive:
                        print(">> your code is here on scene become inactive")
                    case .background:
                        print(">> your code is here on scene go background")
                    default:
                        print(">> do something else in future")
                }
            }
    }
}

backup