VIEWDID出现在什么时候self.view.window?.rootViewController?。调用dismission(animated:true,completion:nil)

我有出租车管理应用程序,其中一个类调用 堆芯控制器 扩展自 使用所有常用函数。这里我们添加了通知观察器和移除器

override func viewDidAppear(_ animated: Bool) {
    //registering gcm reciever
    super.viewDidAppear(animated)
    NotificationCenter.default.addObserver(self,
                                           selector: #selector(showReceivedGCMMessageCore(_:)),
                                           name: NSNotification.Name(rawValue: appDelegate.messageKey), object: nil)
}
override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)
     NotificationCenter.default.removeObserver(self, name: NSNotification.Name(rawValue: appDelegate.messageKey), object: nil)
}

我的视图控制器

class MyViewController: Corecontroller{
  override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
  }
  override func viewDidDisappear(_ animated: Bool) {
     super.viewDidDisappear(animated)
 }
}

当FCM到达时,它将在内部执行功能 接受请求视图控制器 从我的扩展核心控制器,在这个 接受请求视图控制器

let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let rootController   = kStoryBoard.main.instantiateViewController(withIdentifier:kViewControllers.mainPage) as! MainViewController

    appDelegate.window?.rootViewController = rootController

    self.view.window?.rootViewController?.dismiss(animated: true, completion: nil)

已将新的viewcontroller初始化为rootviewcontroller并已解除,但在本例中 我的视图控制器 viewDidAppear() 执行函数只是想知道为什么会发生这种情况?