SwiftUI Animation very Laggy on iOS 18 Release only

Dear Experts,

I created a SwiftUI View (in a UIKit based project) whose objective is to display a short animation in the front of the user screen. I developed it 8 month ago in XCode 15 for iOS 17, no problems.

But since iOS 18, I can observe huge lags on my animation only in Release app. The problem is not present in Debug app.

I don't understand why this problem occurs, the animation is quite simple, it's just an offset deplacement.

I tried many thing like:

  • Show the animation with a UINavigationController
  • Show the animation with a UIWindow
  • Move the view with .position
  • Remove the GeometryReader
  • All other animation
  • withAnimation and .animation
  • Task and DispatchQueue
  • Etc...

I found that the laggy animation occurs when I set the Optimization Level for the Swift Compiler - Code Generation to Optimize for Speed [-O]. That's very strange because we had this option on Release for iOS 17 and we had no lags...

I can share to you a Sample Repository with the configuration we have. https://github.com/Thibma/sample-animation-swiftui

Today the only option I used is to develop this feature in UIKit but it's too bad to skip the SwiftUI opportunity. :/

If you have any ideas to resolve this, I take !

Thank you !

SwiftUI Animation very Laggy on iOS 18 Release only
 
 
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