title: keyboard done key action swift iOS doesn't work
body: <p>I'm new in stackoverflow, I have a problem with new swift code.
  I have custom the return button on keyboard with "Done", but when I tap on it, don't befall anything... How can I hide the keyboard on tap it? 
  I have added a code (found on this site) for hide the keyboard when you tap somewhere ,not in the keyboard, but I can't custom it with tap on "done" button... Thank you before!!</p>