iOS 13 breaks UIViewPropertyAnimator transition

Question

Created Aug ’19

Replies 2

Boosts 0

Views 2.6k

Participants 3

Hi there,
We have a broken transition in WeatherKit only reproducible on iOS 13 beta. We're unsure if this is an UIKit bug or we're doing something awfully wrong.
With an array of

UIViewPropertyAnimator working before iOS 13, ever since iOS 13 (through all of the betas)

the animation frame is not updating correctly. For example: I have an

UIViewPropertyAnimator

called

labelAnimator

which animates a label to some specific

CGRect

, that

CGRect

is not respected and the label animates somewhere else.

Here's a video of the issue: https://www.youtube.com/watch?v=BcgkQp2zIsk
(iOS 13 on the left, iOS 12 on the right).
Also, here's a public gist with the code of the transition:
https://gist.github.com/perteadrian/2c85188b2aacc929b2dfa7842e615c41
Thanks!

Boost

Answer 1

lightbow OP

Aug ’19

Something's definitely different with animations in iOS 13. I'm seeing a few cases in my app where the interactive-drag animation just jumps to the final location/value. Fine on < iOS 13 but broken in the betas. Still trying to determine whether it's my misuse, or an actual break.

0

Answer 2

cp101 OP

Sep ’19

I observed something similar with the progress property of an UIProgressView that I animated to go down to zero. On iOS 12 it vanishes smoothly, on iOS 13 it disappears when the UIPropertyAnimation starts.

I fixed it by letting progress drop to Float.leastNonzeroMagnitude instead of 0.

So either UIProgressView or UIPropertyAnimation is buggy. Try to replace one of your zero target values by something slightly bigger than zero. If that helps, I guess UIPropertyAnimation is the culprit.

0