Hello,
Thank you for your reply. Here are the details we observed:
• iOS 18.6.2 (current release):
authenticateHandler is invoked consistently — both when the Game Center sign-in UI appears and when the user taps Cancel.
• iOS 26.0 beta 1 (first available build):
Regression begins here. The Game Center sign-in UI is shown automatically, but pressing Cancel does not invoke authenticateHandler. The app receives no callback.
• All subsequent iOS 26 betas (beta 2, beta 3, and the latest beta):
Same behavior as beta 1. The issue has been reproducible across every iOS 26 beta so far.
• Xcode versions used for testing:
• Xcode 16.0 beta 1 with iOS 26.0 beta 1
• Xcode 16.0 beta 2 with iOS 26.0 beta 2
• Xcode 16.0 beta [latest] with iOS 26.0 beta [latest]
So the regression is present from the very first iOS 26 beta through the latest beta.
To help with investigation, I will provide a minimal sample project that sets GKLocalPlayer.local.authenticateHandler in viewDidAppear and logs when the handler is called. On iOS 18.6.2 (release), the Cancel action produces a callback. On iOS 26 betas it does not.
Minimal Sample Project:
https://github.com/egorafanasenko/GameCenterAuthiOS26Bug
I've also filed a Feedback Assistant report with the sample project and sysdiagnose logs attached.
