title: Ionic 2: How to handle the hardware back button which checks confirmation of Exit in app
body: <p>I am facing an issue how to handle the default mobile's back button which checks the confirmation while exiting from the application, if I pressed the back button there should invoke some handler which shows pop-up, for confirm exiting.
  OR there is any method call registerBackButtonAction()? or is it so how to use it in <strong>IONIC 2</strong>,?
  Please help me out. Thanks in Advance.</p>