title: Swift 2 - Pattern matching in "if"
body: <p>Recently I've saw the WWDC 2015 keynote from Apple. I also looked at some documentation but I can't find a "pattern matching in if" section, how it was written on one of the slides which they have shown.
  (68min 00sec video from <a href="http://www.apple.com/live/2015-june-event/">Apple Events</a>)</p>
  
  <p>Do you know what's this refers to? Or the syntax?</p>