Xcode 4.6.2 seems quite buggy.
When I run a second time my any project I get SIGABRT crash within the first second. I completely removed Xcode and reinstal
I suppose it has something to do with the latest update of iTunes (11.0.4), because I ran into the same issue after installing the update.
We might have to wait until Apple fixes this problem and go on with the above solutions which seem to work for me also.