Leaking views when changing rootViewController inside transitionWithView

Question

While investigating a memory leak I discovered a problem related to the technique of calling setRootViewController: inside a transition animation block:

Answer 1

I try a simple thing which work for me on iOs 9.3 : just remove the old viewController's view from its hierarchy during dismissViewControllerAnimated completion.

Let's work on X, Y, and Z view as explained by benzado :

That is, this sequence of operations...

1. X becomes Root View Controller
2. X presents Y, so that Y's view is on screen
3. Using transitionWithView: to make Z the new Root View Controller

Which give :

////
//Start point :

let X = UIViewController ()
let Y = UIViewController ()
let Z = UIViewController ()

window.rootViewController = X
X.presentViewController (Y, animated:true, completion: nil)

////
//Transition :

UIView.transitionWithView(window,
                          duration: 0.25,
                          options: UIViewAnimationOptions.TransitionFlipFromRight,
                          animations: { () -> Void in
                                X.dismissViewControllerAnimated(false, completion: {
                                        X.view.removeFromSuperview()
                                    })
                                window.rootViewController = Z
                           },
                           completion: nil)

In my case, X and Y are well dealloc and their's view are no more in hierarchy !