UIPresentationController and its instance methods presentationControllerDidDismiss...:

For the documentation, send a bug report.

What is your problem ? What do you get, what do you expect ?

No you don't need to implement them for a custom presentation. These are new iOS 13 delegate methods that allow customisation of non custom presentations (UIModalPresentationStyle.automatic) see https://developer.apple.com/videos/play/wwdc2019/224/

I already filed a bug report.

I have a few problems:

1. I do not know under which conditions presentationControllerDidAttemptToDismiss: and presentationControllerShouldDismiss: are sent. So, I also do not know what to do with them. I have found presentationControllerDidAttemptToDismiss: in a demo program from Apple somewhere and did a similar implementation in my app but actually I do not know what I am doing here.
2. When writing your own UIPresentationController I assume that I have to call these methods at appropriate times. And I would like to know when to do it (

   presentationControllerWillDismiss: and 

   presentationControllerDidDismiss: are obvious

   ).
3. It seems to be that UIPresentationController even has its own blocks (e.g. _sendDismiss) for handling these messages. Therefore, I expect that it might not be sufficient just to send these messages but that there are some additional conditions / preparations required.

Thanks for the link.

But I think that you have misunderstood my question. I am implementing my own UIPresentationController and I have to / should send these messages from this controller, too.