I just upgraded my old project to new iOS 7. It was already using Cocoapods. I compile and run and everything works fine on the simulator and the device. I tried to archive
I had this problem when experimenting with adding CocoaPods to an existing project.
It turned out that CocoaPods got the Architectures setting right, but missed on the Build Active Architecture Only setting. Both must be in perfect sync with your main project, or it will fail when building for a real device (at least if you got more than one ARM arch, which you usually do (armv7, armv7s and now arm64)).
Solved the problem for me, hopefully this will help others with a similar problem.