fix: Stop CA animations from leaking onto recycled layers#9508
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Animations were created with removedOnCompletion=NO and fillMode=kCAFillModeBoth, so once an opacity transition finished it kept painting its toValue over the model layer forever. When RN later recycled that layer onto a different view, the lingering animation hid (or showed) the new view incorrectly - 'components that weren't animated with core animation disappear'. Switch to removedOnCompletion=YES + fillMode=kCAFillModeBackwards, and commit toValue to the model in the same setDisableActions transaction as the addAnimation: call. The model holds toValue throughout the animation's lifetime; once the animation auto-removes, the layer simply reads the model and there's no snap. Stale animations can no longer outlive their duration.
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Summary
Animations were created with
removedOnCompletion=NOandfillMode=kCAFillModeBoth, so once an opacity transition finished it kept painting its toValue over the model layer forever. When RN later recycled that layer onto a different view, the animation was incorrectly applied to views that shouldn't be animated.To fix the issue, we switched to
removedOnCompletion=YES+fillMode=kCAFillModeBackwards, and committoValueto the model in the samesetDisableActionstransaction as theaddAnimationcall. The model holdstoValuethroughout the animation's lifetime; once the animation auto-removes, the layer simply reads the model and there's no snap. Stale animations can no longer outlive their duration.Example recording
Parts of the app were disappearing on each navigation to the screen in which just a single component was using a Core Animation
Simulator.Screen.Recording.-.iPhone.17.Pro.-.2026-05-22.at.21.12.12.mp4