PushNotificationIOS.addEventListener()

Attaches a listener to remote or local notification events while the app is running in the foreground or the background.

Valid events are:

• notification : Fired when a remote notification is received. The handler will be invoked with an instance of PushNotificationIOS.
• localNotification : Fired when a local notification is received. The handler will be invoked with an instance of PushNotificationIOS.
• register: Fired when the user registers for remote notifications. The handler will be invoked with a hex string representing the deviceToken.