Find and restore deleted files in your Git history (on OS X)
The easiest way I've found for restoring files that I've deleted at some point in my project from Git is to use GitX.
Simply find the commit where you deleted the files you want in the History window, then select and drag the files you want from the previous commit on to your desktop. (You can then drag the files into Xcode to add them to your project again).
git add . to add them to the repository again, commit, push, and Bob's your uncle.