title: Unable to make outlet connection to a constraint in IB
body: <p>I am running XCode 5 with iOS 7.  I need to dynamically change the height constraint of a UITextView prior to its layout.  I have seen many postings stating that this can be done by making an outlet connection from the constraint in IB to the source code.  I am trying to make the connection from the constraint outlet in IB to the header file of the owning class, but am unable to make the connection  - IB does not "highlight" when I drag over the header file, as it does when making connections from other objects like buttons etc.</p>
  
  <p>Has anyone encountered this before?  All help is greatly appreciated.</p>