Want to build in Xcode 26 b3 on macOS 26 b3? You may have problems with Icon Composer icons, which may not work on previous versions of macOS. Here’s a workaround.
Icon Composer
To avoid your app’s icon going into the sin bin, replace it with one generated by Icon Composer. But that in turn requires overhauling some windows, and there’s a catch in NSLog waiting to get you.
App icons in Tahoe are forced into squares with rounded corners and aren’t allowed to deviate, but add rendering modes for the user. Finding good solutions that remain distinctive isn’t easy.
The Eclectic Light Company 