I have already filed a bug report with a sample project via Feedback Assistant: FB22760723
When presenting a UIViewController using UIModalPresentationFormSheet alongside UISheetPresentationController with a small custom detent (e.g., around 300pt height), VoiceOver spatial swipe navigation breaks.
The user is unable to swipe left or right to navigate sequentially through the accessible elements inside the sheet. Accessibility Inspector reveals that the focus seems to get trapped by the background layer (UIDimmingView / "dismiss popup").
If the sheet is taller (e.g., 600pt), the issue does not occur and swipe navigation works as expected
Steps to Reproduce:
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Run the attached sample Objective-C/UIKit project.
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Turn on VoiceOver.
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Tap the “Open transparent modal” button to present the modal with UIModalPresentationOverFullScreen presentation.
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Tap the "Open form sheet" button to present the sheet (configured with a custom 300pt detent).
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Attempt to swipe right using VoiceOver to navigate to the next element (e.g., from the title label to the buttons).
Expected Results: VoiceOver should smoothly navigate through the sequential accessibility elements inside the sheet's view hierarchy, respecting the bounds of the modal sheet.
Actual Results: VoiceOver gets stuck. The swipe right/left gestures fail to move focus to the next element inside the sheet. Instead, focus often escapes to the background or doesn’t change completely.