title: Nested closures does not like argument list
body: <p>A UIView needs to change a warning label depending on the completion handler of a custom control:</p>
  
  <pre><code>    voucherInputView.completionHandler = {[weak self] (success: Bool) -&gt; Void in
  
          self?.proceedButton.enabled = success
          self?.warningLabel.alpha = 1.0
  
          if success
          {
              self?.warningLabel.text = "Code you entered is correct"
              self?.warningLabel.backgroundColor = UIColor.greenColor()
          }
          else
          {
              self?.warningLabel.text = "Code you entered is incorrect"
              self?.warningLabel.backgroundColor = UIColor.orangeColor()
          }
  
  
          UIView.animateWithDuration(NSTimeInterval(1.0), animations:{ ()-&gt; Void in
              self?.warningLabel.alpha = 1.0
          })
  </code></pre>
  
  <p>The final animation block shows an error in the form.</p>
  
  <pre><code>Cannot invoke 'animateWithDuration' with an argument list of type '(NSTimeInterval), animations: ()-&gt; Void)'
  </code></pre>
  
  <p>If i call this somewhere outside of the completion closure it works.</p>