title: How to show a view controller For incoming call, even device is also locked and application is in background state?
body: <p>I'm currently working on iOS Voip App development, like skype,viber. </p>
  
  <p>Now my problem is when my Application is in Foreground, it shows when incoming call came.But the app is in background state and device is also locked, I want to show my incomingCallViewController for answering the call without unlocking the phone.</p>
  
  <p>How to show a view controller when application is in background state and device is also get locked?</p>
  
  <p>Thanks in Advance.</p>