PubNub's Mobile Push Gateway provides a method to deliver messages fast and reliably regardless of whether the application is in the foreground or background on iOS and Android devices.
PubNub's Mobile Push Notifications feature bridges native PubNub publishing with third-party push notification services including Firebase Cloud Messaging (FCM) and Apple Push Notification Service (APNs). The push gateway is a great way to make sure that you can send important data and messages out to users even when they're not active in your mobile application.
Send and Receive PubNub messages as FCM Push messages on Android and iOS.
Send and Receive PubNub messages as APNS messages on iOS