http://stackoverflow.com/questions/18939421/what-should-xcode-6-gitignore-file-include#
new
Another answer is that there’s a website called gitignore.io , which generates the files based on the .gitignore templates from https://github.com/github/gitignore.
old
The easiest answer is that mine looks like this:
which I believe is the same .gitignore that GitHub sets up with all their repositories by default.