Swift 如何：更新rootViewController IOS 13 SceneDelegate

将rootViewController设置为应用程序状态将保持一个nil值。我在ios 13的场景代理大楼工作

视图控制器的实例化在这里完成

guard let signIn=storyboard.signIn.instantialInitialViewController（）作为？SignenViewController else{break}

从这里开始，signIn的值是nil-即使有一个断点显示成功的实例化

UIApplication.shared.windows.first?.setWithRippleTransition(rootViewController: signIn)
state.rootViewController = signIn

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SceneDelegate.swift干扰了上面设置apps rootViewController的行。Soultion要在那里设置根视图

  let storyboard = UIStoryboard(name: "SignIn", bundle: nil)
  let vc = storyboard.instantiateViewController (withIdentifier: "signIn") as! SignInViewController
  firstVC = vc