Swift: Perform a function on ViewController after dismissing modal

Question

A user is in a view controller which calls a modal. When self.dismissViewController is called on the modal, a function needs to be run on the initial view controller. This function also requires a variable passed from the modal.

This modal can be displayed from a number of view controllers, so the function cannot be directly called in a viewDidDisappear on the modal view.

How can this be accomplished in swift?

Answer 1

How about delegate?

Or you can make a ViewController like this:

typealias Action = (x: AnyObject) -> () // replace AnyObject to what you need
class ViewController: UIViewController {
  func modalAction() -> Action {
    return { [unowned self] x in 
      // the x is what you want to passed by the modal viewcontroller
      // now you got it
    }
  }
}

And in modal:

class ModalViewController: UIViewController {
  var callbackAction: Action?
   override func viewDidDisappear(_ animated: Bool) {
    let x = … // the x is what you pass to ViewController
    callbackAction?(x)
  }
}

Of course, when you show ModalViewController need to set callbackAction like this modal.callbackAction = modalAction() in ViewController