call func in parent UIViewController from last modal UINavigatonController UIViewController - swift

Question

i present a model UINavigationController like so
let flowLayout = UICollectionViewFlowLayout()
let firstViewController = FirstViewController(collectionViewLayout:flowLayout)
let navigationController = UINavigationController(rootViewController: firstViewController)
navigationController.modalPresentationStyle = .fullScreen
present(navigationController, animated: true, completion: nil)
this NavigationController will contain two UIViewcontrollers,
in the last one, when I dismiss the NavigationController, i want to call a function in my main controller before dismissing
I know how to this using protocols and delegates, but only if i use just two UIViewController not a UIViewController and a UINavigationController.
like so
protocol SecondViewControllerDelegate {
func someFunction()
}
class SecondViewController: UIViewController {
var delegate: SecondViewControllerDelegate?
#objc func myRightSideBarButtonItemTapped(_ sender:UIBarButtonItem!)
{
self.delegate?.someFunction()
}
}
do I have to create a CustomNavigationController, or is there any other way like passing the delegate through all ViewControllers

Answer 1

You can write something like:
let flowLayout = UICollectionViewFlowLayout()
let firstViewController = FirstViewController(collectionViewLayout: flowLayout)
firstViewController.delegate = self
let navigationController = UINavigationController(rootViewController: firstViewController)
navigationController.modalPresentationStyle = .fullScreen
present(navigationController, animated: true, completion: nil)
or using callback instead of delegate:
class FViewController: UIViewController {
var onButtonAction: (() -> Void)?
#IBAction onButtonTapped(_ sender: Any) {
onButtonAction?()
}
}
class SViewController: UIViewController {
func someMethod() {
let fVC = FViewController()
fVC.onButtonAction = {}
let navigationController = UINavigationController(rootViewController: fVC)
present(navigationController, animated: true, completion: nil)
}
}