I have designed a new icon for my app/Tahoe in Icon Composer (launched from within Xcode)but I simply cannot get it to show up. The documentation for Icon Composer spends a lot of time describing how to design the icons but goes distressingly vague/silent on how one might use it. It suggests that I should drag the file to Xcode and it will guide me as to where to put it.
The app continues to use the old (pre-Tahoe) icon.
I don't get any change of behaviour and I don't know what to name the file. I assume that there are no other settings that I have to change. I can't find anything on the web or in Apple's documentation: maybe I'm missing something obvious!
My app is a working NSDocument-based Cocoa project.
Any suggestions please.
Tahoe 26.0.1, Xcode 26.0.1, Apple M1 Max MBP.