Bug 217317 – REGRESSION (iOS 14): Incorrectly calculated durations on CSS animation keyframes

• Status: RESOLVED
• Resolution: CONFIGURATION CHANGED
• Component: CSS

Created attachment 410521 [details]
Video showing incorrect animation

With the iOS 14 update, CSS @keyframe animations' keyframes are no longer correctly calculated.
Any iOS prior to 14 works fine and any other browser also animates correctly in comparison.

This has been tested with:
iOS 13 - iPhone 11 and iPhone 8
Chrome 85 - PC
Firefox 81 - PC
Chrome 85 Mac OS 10.14 and 10.15

JSFiddle reproducing the issue:
https://jsfiddle.net/1ao07ng5/

The problem is probably easiest to spot at the 95% -> 100% keyframe.
Based on a 10s animation, this should last for 0.5 seconds but it's animating for much longer

[Radar WebKit Bug Importer]

<rdar://problem/69977262>

[Antoine Quint]

I'm having trouble finding the exact revision point when this would have improved, but I cannot reproduce this with the most recent iOS 14.2 beta. Matthias, can you check with the most recent beta?

[Antoine Quint]

I've also reproduced the issue with the iOS 14 GM build, so I'm confident the issue is gone in iOS 14.2.

It indeed looks like it is working correctly in iOS 14.2 beta

Antoine, do you by chance happen to know the timeline for when iOS 14.2 might be released to the public?

[Antoine Quint]

Mathias, I cannot comment about future iOS release timing. Thanks for checking that it was indeed fixed for you!