title: ios 6 : NSLayoutConstraint issue in iphone 5.1 simulator
body: <p>I am getting an error </p>
  
  <p>Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named NSLayoutConstraint'</p>
  
  <p>when I am trying to run my application in iPhone 5.1 simulator. Iam setting the NSLayoutConstraint for running the project in both 3.5 inch and 4 inch display. If the NSLayoutConstraint is not supporting for iPhone 5.1 simulator, how can I adjust the frames in 3.5 inch and 4 inch display ?</p>