Present a view controller, dismiss it and present a different one in Swift

Question

I have a root view controller that has a button that when the user pushes it, another view controller is presented.

This second controller has a dismiss option that just comes back to the root view controller and a button that when the user touches it dismisses the current view controller so it goes back to the root view controller for a second and presents another one.

Going to the first controller I use:

let vc = FirstController() self.present(vc, animated: true, completion: nil) 

And when in the other view controller I select the button that only dismisses I do this.

self.dismiss(animated: true, completion: nil) 

So for the second controller that needs to dismiss and present another one I have tried the following:

self.dismiss(animated: true, completion: {     let vc = SecondController()     self.present(vc, animated: true, completion: nil) }) 

But I get an error:

Warning: Attempt to present <UINavigationController: 0xa40c790> on <IIViewDeckController: 0xa843000> whose view is not in the window hierarchy!

Answer 1

The error occurs because you are trying to present SecondController from FirstController after you have dismissed FirstController. This doesn't work:

self.dismiss(animated: true, completion: {     let vc = SecondController()      // 'self' refers to FirstController, but you have just dismissed     //  FirstController! It's no longer in the view hierarchy!     self.present(vc, animated: true, completion: nil) }) 

This problem is very similar to a question I answered yesterday.

Modified for your scenario, I would suggest this:

weak var pvc = self.presentingViewController  self.dismiss(animated: true, completion: {     let vc = SecondController()     pvc?.present(vc, animated: true, completion: nil) })