Touch events lost in bottom 10% to 20% of screen when rapidly tapping

• Component: UI Events
• Status: NEW ---

[Steven Yau]

Example: https://yaustar.github.io/ios-touch-issue.html
Source: https://github.com/yaustar/yaustar.github.io/blob/master/ios-touch-issue.html

The text at the top shows the number of changed touches, the id of the first changed touch in the event, the X / Y position of the first changed touch in the event.

Touching the left side of the screen makes it go white, the right, red

When rapid tapping the left and right of the screen (0.5s between each touch) in middle or top (portrait), the screen will flip between white and red.

When doing the same at the bottom 10% or 20% of the screen, some touches are lost so the screen stays white or red.

Is there some extra logic happening at the bottom 10/20% of the screen?

[Steven Yau]

Created attachment 431544 [details]
Video of touch events being lost

This video shows me tapping the screen left/right on the bottom section of the screen where the screen stays white or red despite multiple taps.

When tapping the middle, the colours swap as expected.

[Radar WebKit Bug Importer]

<rdar://problem/79664690>