Exists to explore fixes to an interesting gotcha I had in my MultiPlatform SwiftUI app Purrticles with the combination of:
- An "Applied" view which only showed controls with non-default values
- Using a button with buttonRepeatBehavior
- The crash triggered by a button bound to a UInt
The combination resulting in, when you hold down the "-" button, as it hits zero and the control vanishes, the app crashes.
The crash is because the auto-repeat keeps going whilst the button is invisible.
A near-identical stepper at the bottom of the screen doesn't vanish on count zero - it just stops responding to the '-'button.
Also posted the bug on StackOverflow
Note that the branches on this sample show a few different explorations so have been left in the repo.
This is a very simple example compared to the Purrticles control view which replicates the XCode particle editor (plus additional controls).
The first commit exhibits a related but different bug when a simple VStack is used.
Start holding down the "-" button so the count reduces towards zero.
Instead of a crash, the button vanishes as expected but when you press the Reset Count button to make it reappear, the auto-press of the button is still active and keeps going until the control disappears again.
The apple bug is real, filed as FB15477204 and as rdar://FB15477204 but in doing all these writeups, had an idea.
This is a race condition bug - the condition to remove it from the view is being evaluated before the .disabled clause on the button.
So, what's a good way to delay removal? Add an animation!
The branch AnimatingFixes shows this working.