Problem is solved. the above crash nothing to do with iOS 9 or Xcode 7. we were pushing the app through the MDM(Mobile device Management). MDM was doing a wrapping which was caused to this issue. this was identified by MDM support team. and its working now.
Sorry that I hadn’t mentioned about MDM in my post(because I didn’t thought that MDM can cause such problem)
Thanks for your comments.
solved app crashes on iOS 9