xcode - SwiftUI 从 SceneDelegate sceneDidBecomeActive 加载 View

Question

我正在尝试了解如何从 Swift 函数代码加载 SwiftUI View 。在这个具体情况，我想在从后台状态返回到覆盖敏感数据。我已经创建了一个生物识别登录并且工作正常 - 纯应用程序的 SwiftUI View 。当我将应用程序置于后台并返回时，FaceID 按预期工作，但底层屏幕是可见的。这是一个广义的还有一个问题 - 如何从任何 Swift 函数加载任何 SwiftUI View 。

func sceneDidBecomeActive(_ scene: UIScene) {

    if userDefaultsManager.wentToBackground {
        if userDefaultsManager.enableBiometrics {
            BiometricsLogin(userDefaultsManager: userDefaultsManager).authenticate()
            //what I want is something like:
            //BiometricsLogin(userDefaultsManager: userDefaultsManager)
            //kinda like you would do in a TabView
            //that would run the authentication just like starting the app
            userDefaultsManager.wentToBackground = false
        }
    }
}

登录代码非常通用:

struct BiometricsLogin: View {
    @ObservedObject var userDefaultsManager: UserDefaultsManager

    var body: some View {
        NavigationView {
            VStack {
                Image("CoifMeCrop180")
                .onAppear {
                    self.authenticate()
                }
            }//vstack
        }//nav
    }

    func authenticate() {
        let context = LAContext()
        var error: NSError?

        if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
            let reason = "The app uses Biometrics to unlock you data"
            context.evaluatePolicy(.deviceOwnerAuthentication, localizedReason: reason) { (success, authenticationError)
                in
                DispatchQueue.main.async {
                    if success {
                        self.userDefaultsManager.isAuthenticated = true
                        self.userDefaultsManager.selectedTab = 1
                    } else {
                        if self.userDefaultsManager.enableBiometrics {
                            self.userDefaultsManager.isAuthenticated = false
                            self.userDefaultsManager.selectedTab = 3
                        } else {
                            self.userDefaultsManager.isAuthenticated = false
                            self.userDefaultsManager.selectedTab = 1
                        }
                    }
                }
            }
        } else {
            //no biometrics - deal with this elsewhere
            //consider an alert here
        }
    }//authenticate
}

我也尝试过使用这样的托管 Controller ，但它也没有用。相同的问题，身份验证有效，但数据可见。

    //this does not work
    let controller = UIHostingController(rootView: BiometricsLogin(userDefaultsManager: userDefaultsManager))
    self.window!.addSubview(controller.view)
    self.window?.makeKeyAndVisible()

任何指导将不胜感激。 Xcode 11.3.1 (11C504)

Answer 1

这是可行的方法

在 sceneDidBecomeActive 中添加全屏显示带有身份验证的新 Controller 以隐藏敏感内容

    func sceneDidBecomeActive(_ scene: UIScene) {
        let controller = UIHostingController(rootView: BiometricsLogin(userDefaultsManager: userDefaultsManager))
        controller.modalPresentationStyle = .fullScreen

        self.window?.rootViewController?.present(controller, animated: false)
    }

现在它需要在身份验证完成时关闭它，因此为此目的添加通知...

extension SceneDelegate {
    static let didAuthenticate = Notification.Name(rawValue: "didAuthenticate")
}

... 并在 SceneDelegate 中订阅它

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    private var authenticateObserver: AnyCancellable?

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

        let contentView = ContentView()

        if let windowScene = scene as? UIWindowScene {
            self.authenticateObserver = NotificationCenter.default.publisher(for: SceneDelegate.didAuthenticate)
                .sink { _ in
                    self.window?.rootViewController?.dismiss(animated: true)
                }

            let window = UIWindow(windowScene: windowScene)
            ...

身份验证完成后，只需发送 didAuthenticate 通知即可关闭顶级 Controller

   DispatchQueue.main.async {
        if success {
            self.userDefaultsManager.isAuthenticated = true
            self.userDefaultsManager.selectedTab = 1
        } else {
            if self.userDefaultsManager.enableBiometrics {
                self.userDefaultsManager.isAuthenticated = false
                self.userDefaultsManager.selectedTab = 3
            } else {
                self.userDefaultsManager.isAuthenticated = false
                self.userDefaultsManager.selectedTab = 1
            }
        }
        NotificationCenter.default.post(name: SceneDelegate.didAuthenticate, object: nil)
    }