UIViewController.presentationController is not updated if the transitioningDelegate returns a custom presentation controller

Number:rdar://42996292 Date Originated:07-Aug-2018 11:53 AM
Status:Open Resolved:
Product:iOS + SDK Product Version:iOS 11.4.1
Classification:Other Bug Reproducible:Always
UIViewController allows users to vend a custom presentation controller by means of the UIViewControllerTransitioningDelegate protocol. However, if the view controller’s presentation controller is accessed before setting the transitioning delegate, then the transitioningDelegate is never queried for the presentation controller. This results in unexpected behaviour.

Steps to Reproduce:
Run the attached sample project.

Expected Results:
The “Presentation controller now: %@“ line logs
“Presentation controller now: <CustomPresentationController: 0x123>”

Actual Results:
The “Presentation controller now: %@“ line logs
“Presentation controller now: <_UIFullscreenPresentationController: 0x123>”

iOS 11.4.1

If you comment out line 30 (where the default presentationController is accessed), you will notice that the expected presentation controller is returned.


Link to sample


Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at bugreport.apple.com before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!