UIViewControllerTransitioningDelegate being deinitialized immediately after it is presented - ios

Question

I'm trying to present a view controller modally with a custom presenter using UIPresentationController (and UIViewControllerTransitioningDelegate).
The problem is that the transitioning delegate is being deinitialized immediately after animationController(presented:presenting:source:) is called. This means animationController(dismissed:) never gets called - and thus, a dismissal animation cannot be set.
In the end, I want to be able to define the dismissal animation. I believe what I explained above is the root of the problem, but can't find anything about this online.
Here is my implementation of UIViewControllerTransitioningDelegate:
final class Manager: NSObject, UIViewControllerTransitioningDelegate {
private let size: CGSize
var animator: Animator
init(size: CGSize) {
self.size = size
self.animator = Animator(duration: 0.4, loaf: loaf)
}
deinit {
print("DEINIT") // 2) Then this is being called immediately after
}
func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
return Controller(
presentedViewController: presented,
presenting: presenting,
size: size
)
}
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
animator.presenting = true
return animator // 1) This is called first after the view controller is presented
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
animator.presenting = false
return animator // 3) This is never called
}
}
And this is how I'm setting the transitioning delegate:
extension UIViewController {
func presentModally(_ viewController: UIViewController, size: CGSize) {
viewController.transitioningDelegate = Manager(size: size)
viewController.modalPresentationStyle = .custom
present(viewController, animated: true)
}
}
When the view controller is then dismissed, the view always defaults to being pushed down and disappearing. Again, animationController(dismissed:) is never called and I can't figure out why.

Answer 1

I was able to fix this by storing a reference to the UIViewControllerTransitioningDelegate on the presenting view controller. Then, when presenting the modal, set it like this:
extension UIViewController {
func presentModally(_ viewController: UIViewController, size: CGSize) {
viewController.transDelegate = Manager(size: size)
viewController.transitioningDelegate = viewController.transDelegate
viewController.modalPresentationStyle = .custom
present(viewController, animated: true)
}
}