title: Check if a func exists in Swift
body: <p>I wish to check if a func exists before I call it. For example:</p>
  
  <pre><code>    if let touch: AnyObject = touches.anyObject() {
          let location = touch.locationInView(self)
          touchMoved(Int(location.x), Int(location.y))
      }
  </code></pre>
  
  <p>I would like to call touchMoved(Int, Int) if it exists. Is it possible?</p>