Adding a View to a Window Hierarchy

Question

I am trying to create a pause screen in my game. I added a viewController to the "PauseScreen" storyboard panel with the storyboard ID and recovery ID set to "PauseScreenID", and to go to the pause screen, I created a function in the "GameScene":

func pauseSceenTransition(){ let viewController = UIStoryboard(name: "Main", bundle:nil).instantiateViewControllerWithIdentifier("PauseScreenID") as UIViewController let currentViewController = (UIApplication.sharedApplication().delegate as AppDelegate) currentViewController.window?.rootViewController?.presentViewController(viewController, animated: false, completion: nil) } 

However, when it is called, I get an error message:

Warning: try presenting <AppName.PauseScreen: 0x7fae61fe5ff0> in <AppName.StartScreenViewController: 0x7fae61f79980>, whose view is not in the hierarchy of windows!

"StartScreenViewController" is the view controller for my start screen and is the start view controller. He then moves on to “GameScene,” where “PauseScreen” should go. It works if I make the initial view controller "GameViewController" / "GameScene", so I assume that I need to change the second line:

 let currentViewController = (UIApplication.sharedApplication().delegate as AppDelegate) 

so that it displays "PauseScreen" in the "GameViewController" and not in the "StartScreenViewController", but I'm not sure how to do it.

Answer 1

The error tells you what exactly is happening.

Warning: Attempt to present <AppName.PauseScreen: 0x7fae61fe5ff0> on <AppName.StartScreenViewController: 0x7fae61f79980> whose view is not in the window hierarchy!

(UIApplication.sharedApplication().delegate as AppDelegate).window?.rootViewController points to an instance of StartScreenViewController . This is bad: rootViewController should point to an instance of GameScene .

The root cause should be how GameScene is GameScene . From your description:

"StartScreenViewController" is the view controller ... Then it goes to "GameScene" ...

That should be your problem. How do you navigate to GameScene from StartScreenViewController ?

I assume that you are adding a new window to the application. You need to install rootViewController .

 let gameScene = UIStoryboard(name: "Main", bundle:nil).instantiateViewControllerWithIdentifier("GameSceneID") as UIViewController let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate) appDelegate.window?.rootViewController = gameScene 

When you return to the start screen, you will install rootViewController again.

 let initialViewController = UIStoryboard(name: "Main", bundle:nil).instantiateInitialViewController() as UIViewController let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate) appDelegate.window?.rootViewController = initialViewController 

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You can use transitionFromViewController(,toViewController:, duration:, options:, animations:, completion:) to animate the settings of the root view controller.