设置rootViewController iOS 13

Question

升级 Xcode 后，我的应用程序的一个关键部分停止工作。

当我的应用启动时，我会运行一个函数来检查布尔标志并设置正确的 rootViewController。

但是我用来设置它的代码现在已经停止工作

class func setLoginAsInitialViewContoller(window:UIWindow) {
    print("SET LOGIN") 
    let storyboard = UIStoryboard(name: "Login", bundle: nil)
    let controller = storyboard.instantiateViewController(withIdentifier: "LoginViewController")
    controller.modalPresentationStyle = .overFullScreen
    window.rootViewController = controller
    window.makeKeyAndVisible()
}

特别是当应用程序获取倒数第二行 window.rootViewController = controller 时，它会崩溃并出现 libc++abi.dylib: terminating with uncaught exception of type NSException 错误。

上面的函数在一个名为 Utilities.swift 的类中，我正在我的 AppDelegate.swift 中调用该函数，如下所示：

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var storyboard: UIStoryboard? = nil

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        UIApplication.shared.isIdleTimerDisabled = true
        Utilities.decideInitialViewController(window: self.window!)

        return true
    }

非常感谢任何关于如何设置根控制器的解决方案或修复。

谢谢！

Answer 1

这是因为 AppDelegate 不再具有 window 属性。 现在您必须使用 SceneDelegate 的 scene(_:willConnectTo:options:) 方法来更改根视图控制器。 如本例所示：

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let scene = (scene as? UIWindowScene) else { return }

        // Instantiate UIWindow with scene
        let window = UIWindow(windowScene: scene)
        // Assign window to SceneDelegate window property
        self.window = window
        // Set initial view controller from Main storyboard as root view controller of UIWindow
        self.window?.rootViewController = UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController()
        // Present window to screen
        self.window?.makeKeyAndVisible()
    }

Answer 2

它在您项目的 SceneDelegate.swift 文件中可用

它将有委托方法：

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

示例

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


if let windowScene = scene as? UIWindowScene {

    self.window = UIWindow(windowScene: windowScene) 

    let initialViewController = 
        storyboard.instantiateViewController(withIdentifier: "FirstViewController")            
        self.window!.rootViewController = initialViewController
        self.window!.makeKeyAndVisible()
    }

}

Answer 3

在viewDidAppear中你可以设置root：-

  override func viewDidAppear(_ animated: Bool) {
            print(self.view.window)
            let vc = self.storyboard?.instantiateViewController(identifier: "SecondViewController") as? SecondViewController
            self.view.window?.rootViewController = vc
        }

Answer 4

• 如果你想使用ScenceDelegate。在scene(_:willConnectTo:options: 中，创建一个新的 UIWindow，设置窗口的rootViewController 并使这个窗口成为key 窗口。
• 如果您不想使用ScenceDelegate，可以尝试将其删除by following this。

Answer 5

对于希望创建几个扩展来更改根视图控制器并需要支持两种委托类型（UISceneDelegate 和 AppDelegate）的任何人，这里有几个：

    extension UIViewController {
        var appDelegate: AppDelegate {
        return UIApplication.shared.delegate as! AppDelegate
    }
    
    var sceneDelegate: SceneDelegate? {
        guard let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
            let delegate = windowScene.delegate as? SceneDelegate else { return nil }
         return delegate
    }
}

如果您需要扩展以从支持 iOS12 和 iOS13 的 ViewController 访问 UIWindow：

extension UIViewController {
    
    var window: UIWindow? {
        if #available(iOS 13, *) {
            guard let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
                let delegate = windowScene.delegate as? SceneDelegate, let window = delegate.window else { return nil }
                   return window
        }
        
        guard let delegate = UIApplication.shared.delegate as? AppDelegate, let window = delegate.window else { return nil }
        return window
    }
}