title: Swift : present a ViewController while alert is shown
body: <p>I have a problem with present UIViewController Modaly by above code</p>
  
  <pre><code>self.presentViewController(view, animated: true, completion: nil);
  </code></pre>
  
  <p>it doesn't work when another view present modaly such as UIAlert,its triggered by a socket packet in background and user may is performing another work and may another modal view already presented when the trigger happens.</p>