I have been experimenting with custom interactive view controller presentation and dismissal (using a combination of UIPresentationController
, UIPercentDrivenInteractiveTransition
, UIViewControllerAnimatedTransitioning
, and UIViewControllerTransitioningDelegate
) and have mostly gotten things working well for my needs.
However, there is one common scenario that I've yet to find addressed in any of the tutorials or documentation that I've read, leading me to the following question:
...
What is the proper way of handling custom interactive view controller dismissal, via a pan gesture, when the dismissed view contains a UIScrollView (ie. UITableView, UICollectionView, WKWebView, etc)?
...
Basically, what I'd like is for the following:
View controllers are interactively dismissible by panning them down. This is common UX in many apps.
If the dismissed view controller contains a (vertically-scrolling) scroll view, panning down scrolls that view as expected until the user reaches the top, after which the scrolling ceases and the pan-to-dismiss occurs.
Scroll views should otherwise behave as normal.
I know that this is technically possible - I've seen it in other apps, such as Overcast and Apple's own Music app - but I've not been able to find the key to coordinating the behavior of my pan gesture with that of the scroll view(s).
Most of my own attempts center on trying to conditionally enable/disable the scrollview (or its associated pan gesture recognizer) based on its contentOffset.y
while scrolling and having the view controller dismissal's pan gesture recognizer take over from there, but this has been fraught with problems and I fear that I am overthinking it.
I feel like the secret mostly lies in the following pan gesture recognizer delegate method:
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
// ...
}
I have created a reduced sample project which should demonstrate the scenario more clearly. Any code suggestions are highly welcome!