iOS 5.1 app crash on startup with Symbol not found: _NSFontAttributeName

Question

I am getting below error while running app on iPad with iOS 5.1.1

dyld: Symbol not found: _NSFontAttributeName
  Referenced from: /var/mobile/Applications/9471D711-BCA7-4529-A584-9747C2E03DBC/egnyteMobileIOSUniversal.app/egnyteMobileIOSUniversal
  Expected in: /System/Library/Frameworks/UIKit.framework/UIKit
 in /var/mobile/Applications/9471D711-BCA7-4529-A584-9747C2E03DBC/egnyteMobileIOSUniversal.app/egnyteMobileIOSUniversal

Where as in my code, i now where use NSFontAttributeName constant .As i am aware it is supported for iOS equal or above 6.0.Neither in my code i am using NSAttributedString Class.
Is that possible that some other method or UI controls is calling in this method internally?
Stack-trace doesnt give me any information on which code or method is getting this issue.
Is there any way by which i can debug trace symbols error properly ? My application supports min 5.0 iOS

Answer 1

Change the Type for UIKit from Required to Weak and rebuild your application target. That should take care of the runtime errors.