Detect if my app is closed

Closest you can get is event that tells you when the App has entered the background. Put this into your .run():

    //handle Cordova resume (enter foreground) and pause (enter background events)
    $ionicPlatform.on('resume', function() {
        
    });

    $ionicPlatform.on('pause', function() {
        //Do something here on entering background
    });