Detecting sheet was dismissed on iOS 13
Before iOS 13, presented view controllers used to cover the entire screen. And, when dismissed, the parent view controller viewDidAppear function were executed.
Now iOS 13 will present view controllers as a sheet as default, which means the card will partially cover the underlying view controller, which means that viewDidAppear will not be called, because the parent view controller has never actually disappeared.
Is there a way to detect that the presented view controller sheet was dismissed? Some other function I can override in the parent view controller rather than using some sort of delegate?
Answer
Is there a way to detect that the presented view controller sheet was dismissed?
Yes.
Some other function I can override in the parent view controller rather than using some sort of delegate?
No. "Some sort of delegate" is how you do it. Make yourself the presentation controller's delegate and override presentationControllerDidDismiss(_:).
The lack of a general runtime-generated event informing you that a presented view controller, whether fullscreen or not, has been dismissed, is indeed troublesome; but it's not a new issue, because there have always been non-fullscreen presented view controllers. It's just that now (in iOS 13) there are more of them! I devote a separate question-and-answer to this topic elsewhere: Unified UIViewController "became frontmost" detection?.