How to get exact PresentingViewController when Modal View dismissed

Question

My App navigation is like below:

NavigationController ---> RootViewController --(Show Segue)-> SomeViewController --(Show Segue)-> ParentViewController (With ContainerView)

So, ParentViewController has a container view. This container view is populated programmatically, at runtime, depending upon user selection. So, basically the view hierarchy is like this:

ParentViewController (With ContainerView) ---(Embed Segue) --> ContainerViewController --(Custom Segue, for deciding which child to show at runtime) ---> FirstChildViewController/SecondChildViewController

Now, I display a modal view when a button is tapped in SecondChildViewController. Everything is fine, till this point.

But, now I want to update data in SecondChildViewController on the dismissal of ModalViewController. I try to do it like this in ModalViewController:

SecondChildViewController *secondChildVC = (SecondChildViewController *)self.presentingViewController;
[self dismissViewControllerAnimated:YES completion: ^{ [secondChildVC updateList];   }];

But, I am getting following error:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UINavigationController updateList]: unrecognized selector sent to instance 0x127e451b0'

How can I fix this issue? So, to be specific, how can I get the "real" presentingViewController? I know its a bit weird navigation, and there is too much stacking on views from user experience point of view, but that is the way client wants to implement.

Answer 1

I am not sure if I understood your question correctly. If you have a ViewController A, presenting ViewController B, and if you wish to call a method in A when B is dismissed - you can make A a delegate of B.

Read more about Protocols and Delegates here: https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/WorkingwithProtocols/WorkingwithProtocols.html