Handling Background and Foreground States for Reliable Notifications

Push notifications behave differently based on app state, device settings, and platform-specific power management rules. FCM and APNs handle foreground vs background notifications differently, with system-managed display in background but developer-controlled handling in foreground. Key challenges include token management, message queueing, app termination effects, and platform-specific limitations like Android's Doze mode and iOS's silent push throttling. Proper implementation requires handling both notification and data message types, managing token refresh, implementing high-priority messaging, and thorough testing across different device manufacturers.