title: Segue not calling prepareForSegue
body: <p>Perhaps I am missing something simple.  I added a modal segue from a button to a view controller.  I then added some steps to prepareForSegue (and checked I had named the segue correctly). I have done this a few other times with no problem.</p>
  
  <p>Now, when I click the button, the modal window opens, but the prepareForSegue does not fire.  I tried putting a log statement in the prepareForSegue before it even checks the description of the label (so theoretically it should fire for any segue).  But I get nothing logged.</p>
  
  <p>Any ideas? </p>