title: UIAlertController subclass issue swift
body: <p>I want to create a UIAlertController's subclass but I'm going crazy because I have problem with constructor, this is my subclass:</p>
  
  <pre><code>class loginAlert :  UIAlertController {
  
      required init?(coder aDecoder: NSCoder) {
          super.init(coder: aDecoder)
  
      }
  
  }
  </code></pre>
  
  <p>I think that this subclass must have the constructor : 
  UIAlertController(title: String, message: String, preferredStyle: UIAlertControllerStyle) , because it's a subclass of UIAlertController , but when I do </p>
  
  <pre><code>loginAlert(title: "test", message: "test", preferredStyle: .Alert)
  </code></pre>
  
  <p>I get error , why where Do I wrong?</p>