title: How do I declare NULL/Void in swift when I don't need to use a completion block?
body: <p><strong>Here is the code in objective-c:</strong></p>
  
  <pre><code>[self presentViewController:logInViewController animated:YES completion:NULL];
  </code></pre>
  
  <p>My code so far in swift:</p>
  
  <pre><code>self.presentViewController(logInViewController, animated: true, completion:  )
  </code></pre>
  
  <p>Thought it would be as straight forward as typing "Void". Unfortunately there's a little more to it.</p>