I've created a new iOS project using Xcode 26 beta 2. This project will have a deployment target of iOS 26.0. I've added 3 glass .icon files to the project, AppIcon.icon, AppIcon2.icon, and AppIcon3.icon. The "App Icon" setting on the General tab has been set to "AppIcon". I've enabled the "Include all app icon assets" option (though that doesn't seem to affect the issue).

If I build and run the app on an iOS 26 simulator, the app's icon is the glass icon from AppIcon.icon. But when my code tries something like:

UIApplication.shared.setAlternateIconName("AppIcon2")

nothing happens. The icon doesn't change. There is no alert telling the user that the icon has been changed.

I can't find any setting in Xcode or the project that lets me specify the alternate icons.

With an iOS 18 or earlier app, the names of the alternate icons are automatically determined from any iOS App Icon entries in any Assets files. But you don't put the new glass .icon files in any assets.

Is this missing functionality in Xcode 26 or am I missing something? How do I make this work?