I hope it works out. What I do, is create a file, usually called something like "DoNotCheckThisIntoSourceControl.swift", and then put that in a directory called "DoNotCheckThisIntoSourceControl". I then add "DoNotCheckThisIntoSourceControl" to my .gitignore.

Clunky, but it works. I add things like server secrets and whatnot, there. I keep the file small, and usually add the contents to a secure note in 1Password, so there is version control, of a sort.