Allows using back button to exit the application (per screen).

Double tap to exit available. Here's the overall procedure:

1. Set the TapTwiceToExit boolean parameter to true, and define a grace period on TabExpiry if necessary (default: 2 seconds)
2. When user taps the native back button, a timeout is setup for the defined expiry period, and BackTap event is triggered. This is where you can show a message saying "Tap back again to leave". Just like 9Gag for Android.
3. If the user taps back again, you're done with him.
4. If he doesn't tab the back button again during the period, a new event BackTapExpired is triggered by the timeout set on 2. This is where you should clear the message, because the first tap was ignored.
5. If the user navigates between the first and second tap, the timeout is reset, and user is able to navigate using back again.

Check the demo!

Works on OutSystems Now, as it only uses standard cordova methods, only instead of exiting OutSystems Now, it goes back to the main screen... Keep tapping back!