Xcode5: Failed to register "/System/Library/CoreServices/CoreTypes.bundle/Contents/Library/MobileDevices.bundle
This appears to be an compiler bug, and there's not much that can be done about it.
Here is oficial answer on JetBrains Tracker:
Anton Makeev 17 Sep 2013, 19:36
build error doesn't affect compilation results - it's just a log message from xcodebuild. Simulator should work correctly after you run it at least once in Xcode 5.
and:
We will handle this output in AppCode (show it as a warning, not a n error) but we recommend filing the error to Apple as the message suggests - unfortunately we can't fix it (only hide)
and:
Build error won't go away until we implement 'hide-it-fix' or until Apple fixes it. It is harmless, though and doesn't affect build result.