With iOS 15 there are changes to keyboard handling. Besides usual overriding of keyCommands a programmer has to assign own commands higher priority than system commands by using wantsPriorityOverSystemBehavior flag. Otherwise, custom actions on key presses won't work.
If we use QLPreviewController we cannot override keyboard presses in iOS 15 when we set wantsPriorityOverSystemBehavior to true. The registered key commands are not working. This functionality was working perfectly before the flag was introduced. It works properly if we use UIViewController, so it seems QLPreviewController was not updated to handle the new iOS flag.
Please see the VIDEO I recorded for you (it includes my audio description, so turn on the volume) for more details. During watching, keep in mind, that PreviewViewController is a subclass of QLPreviewController with overridden keyCommands property (as you can see in the attached demo project).
The overridden keyboard presses should work with QLPreviewController in the same way as they do with UIViewController.
The overridden keyboard presses were ignored by QLPreviewController, but they work fine with UIViewController.
When I clicked on Debug View Hierarchy, I noticed on the top of my PreviewViewController (which is a subclass of QLPreviewController with overriding keyCommands only) there is UINavigationController with QLRemotePreviewCollection. Maybe that last one is capturing keyCommands and since it treats them as top priority, it doesn't pass that information to my instance. The issue is that I do not have access to that QLRemotePreviewCollection to override keyCommands there.
I've submitted it also in:
- https://developer.apple.com/forums/thread/696128
- https://stackoverflow.com/questions/70250053/uikeycommand-in-qlpreviewcontroller-in-ios-15
Please make sure you check it out at any of the links there. It contains manual repro steps. But you can also download & run the code in this repository. It's as short as possible to show the issue.
Please open attached simple demo project to be able to reproduce the issue (you have to build it with iOS 15 SDK). Please follow the red text on the top of the simulator. Reproduction steps are also written in the linked thread (at the end of this bug report description) if you don't want to open the demo project.