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.
The problem may be because of target version in of your project,it may be 5.0 i guess.There is a solution for this problem
step1.Select your project
step2.select the General tab
step3.change the project deployment target.