I have an iOS app that worked well on all devices in iOS 6.
I recently upgraded my xcode to version 5.0 and tried to build the same app for iOS 7 on an iPhone 5.
There is very simple fix. You have just to uncheck "Use Auto Layout" in General tab. More information http://shreekantpawar.com/2012/12/20/simple-solution-to-auto-layout-on-ios-versions-prior-to-6-0-error-in-mac-osx-10-7-and-later/