Fix Modal staying onscreen when dismissed while presenting a child controller

[lazerg]

Summary:

Dismissing a Modal on iOS/Fabric while it was presenting a child view controller (a system alert, an action sheet, the dev menu) left the modal itself stuck onscreen as an empty sheet. RCTModalHostViewComponentView dismissed the modal's view controller directly, but UIKit forwards dismissViewControllerAnimated: calls to the topmost presented child, so only the alert closed while React still thought the modal was gone.

Now the dismissal goes through the modal's presentingViewController whenever it has a presented child, closing the whole stack in one animation.

Fixes #58326

Changelog:

[IOS] [FIXED] - Fix Modal staying onscreen when dismissed while presenting a child view controller

Test Plan:

Added RCTModalHostViewComponentViewTests.mm: dismissing with a presented child redirects through presentingViewController, falls back to the modal itself when that's nil, and the no-child path still dismisses directly. Couldn't run against a simulator in this environment (no full Xcode/CocoaPods toolchain available here); traced the issue's repro steps against the new logic by hand.

[cipolleschi]

Thanks for fixing this.
Code makes sense. Can you add a video in the Test Plan using the same reproducer of the issue that shows that the issue is fixed?

[mozzius]

@cipolleschi patching this into bluesky-social/social-app does fix the bug!

ScreenRecording_09-10-2026.11-15-26_1.mp4

[meta-codesync]

@cipolleschi has imported this pull request. If you are a Meta employee, you can view this in D119478518.

[lazerg]

@cipolleschi I can't record a video. This sandbox has no iOS Simulator or device, so I can't run the app reproducer.

Instead, I modeled the UIKit rule that causes the bug: dismissViewController always forwards to the topmost presented child. I ran that model before and after the fix.

Before the fix: the alert closes, but the modal stays onscreen as an empty sheet.
After the fix: the alert and the modal both close.

Output:

--- BEFORE fix ---
events: ['onDismiss fired']
alert.on_screen:  False
modal.on_screen:  True  (BUG: modal stuck onscreen as empty sheet)

--- AFTER fix ---
events: ['onDismiss fired']
alert.on_screen:  False
modal.on_screen:  False  (modal correctly dismissed)

This isn't the real app repro, just the dismiss logic in isolation. The PR also adds RCTModalHostViewComponentViewTests.mm, which covers the same logic through XCTest. I can't compile or run that here either, since this environment has no Xcode toolchain. I traced it by hand against the new code and it matches.

[meta-codesync]

@cipolleschi merged this pull request in f20f857.