title: Can't give parameter values to extension method UIAlertController
body: <p>I am trying to write an extension method that generates an UIAlertController based on what you give as a parameter.</p>
  
  <pre><code>extension UIAlertController {
     func generate(messageText: String, messageTitle: String, buttonText: String) {
         let alert = UIAlertController(title: messageTitle, message: messageText, preferredStyle: UIAlertControllerStyle.Alert)
         alert.addAction(UIAlertAction(title: buttonText, style: UIAlertActionStyle.Default, handler: nil))
         self.presentViewController(alert, animated: true, completion: nil)
     }
  }
  </code></pre>
  
  <p>This doesn't give an error.</p>
  
  <p>But when I try to call it and add the parameter values</p>
  
  <pre><code>var alertTest = UIAlertController.generate("")
  </code></pre>
  
  <p>It gives the following error:  <code>Type 'UIAlertController' does not conform to protocol 'StringLiteralConvertible'</code></p>
  
  <p>How can I fix this?</p>
  
  <p>Or isn't it possible what i am trying to achieve?</p>