使用 SwiftUI 的新 iOS 14 生命周期访问 AppDelegate 中的 AppState

Question

我正在使用 SwiftUI 的新应用程序生命周期 iOS 14.

但是，我一直不知道如何在 AppDelegate 中访问我的 AppState（单一事实来源）对象。我在启动时需要 AppDelegate 到运行代码并注册通知（didFinishLaunchingWithOptions、didRegisterForRemoteNotificationsWithDeviceToken、didReceiveRemoteNotification）等

我知道 @UIApplicationDelegateAdaptor 但我不能，例如使用构造函数将对象传递给 AppDelegate。我想反过来（在 AppDelegate 中创建 AppState，然后在 MyApp 中访问它）也不行。

@main
struct MyApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    @State var appState = AppState()
    
    var body: some Scene {
        WindowGroup {
            ContentView().environmentObject(appState)
        }
    }
}

class AppDelegate: NSObject, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
        // access appState here...
        return true
    }

    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        // ...and access appState here
    }
}

class AppState: ObservableObject {
    // Singe source of truth...
    @Published var user: User()
}

感谢任何帮助。也许目前没有办法实现这一点，我需要转换我的应用程序以使用旧的 UIKit 生命周期？

Answer 1

为 AppState

使用共享实例

class AppState: ObservableObject {
    static let shared = AppState()    // << here !!

    // Singe source of truth...
    @Published var user = User()
}

所以你可以在任何地方使用它

struct MyApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    @StateObject var appState = AppState.shared

    // ... other code
}

和

    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        // ...and access appState here

        AppState.shared.user = ...
    }

backup

Answer 2

您需要运行应用程序委托中的代码的原因是什么？如果您正在使用新的应用程序生命周期，为什么不从 WindowGroup.onChange()

触发您的代码

struct MyScene: Scene {
    @Environment(\.scenePhase) private var scenePhase
    @StateObject private var cache = DataCache()

    var body: some Scene {
        WindowGroup {
            MyRootView()
        }
        .onChange(of: scenePhase) { newScenePhase in
            if newScenePhase == .background {
                cache.empty()
            }
        }
    }
}

Apple Documentation Link

Managing scenes in SwiftUI by Majid

使用 SwiftUI 的新 iOS 14 生命周期访问 AppDelegate 中的 AppState

Accessing AppState in AppDelegate with SwiftUI's new iOS 14 life cycle

swift

swiftui

state

appdelegate

ios14