The answer from atbf is what helped me. You have to change the project setting build location and you have to close and reopen the project.

It's not actually hanging, it just takes a really long time. Keep your eye on the Finder status bar to see your hard drive slowly filling.

This isn't really a very useful solution. This change may bring down compile times but compile times are still atrociously slow. You change one line of one final class and it takes Xcode over a minute to recompile. That's criminal.

The rule you are breaking is that capitalization matters when you spell a name. You're saying xFile = ... So the Swift compiler looks for the term xFile declared as a variable name in scope, to which something can be assigned. But the word xFile doesn't appear as a variable name in scope — just as the compiler is telling you. What does appear as a variable name in scope is xfile, which as far as Swift is concerned is a totally different name.

Bump. I repeat the question. Xcode 13 is final. I need the Vary For Traits feature. Some of my apps use it. Where is it?

The way to see all environment variable values is to add a run script to your build phases.