Push Notification Best Practices

Overview

Comprehensive guide for implementing and troubleshooting push notifications in mobile applications. Covers iOS (APNS), Android (FCM), React Native, Expo, and Flutter platforms with platform-specific configurations, token management, message handling, and deep linking patterns.

Platform Support Matrix

Platform	Offline Push	Notification Bar	Click Navigation	In-App Toast	Background Handler
iOS	APNS	System	Deep Link	Custom	data-only payload
Android	FCM	System	Intent	Custom	data-only payload
React Native	APNS/FCM	System	React Navigation	Custom	setBackgroundMessageHandler
Expo	Expo Push	System	Linking	Custom	TaskManager
Flutter	APNS/FCM	System	Navigator	Custom	onBackgroundMessage

Decision Trees

Permission Request Timing

When to request notification permission?

User installing app
        |
        v
  [First launch?] ──Yes──> [Show value proposition first]
        |                          |
        No                         v
        |                  [User action triggers need?]
        v                          |
  [Already granted?]              Yes
        |                          |
       Yes                         v
        |                  [Request permission] ──> 70-80% acceptance rate
        v
  [Notifications ready]

Timing	Acceptance Rate	Use Case
Immediate (app launch)	15-20%	Low engagement apps
After onboarding	40-50%	Standard apps
User-initiated action	70-80%	High engagement apps

Recommendation: Request after explaining value or when user enables a related feature.

Silent vs Visible Notification

Which payload type should I use?

[What's the purpose?]
        |
        +──> Time-sensitive user alert ──> Visible (notification payload)
        |
        +──> Background data sync ──> Silent (data-only payload)
        |
        +──> Custom UI required ──> Silent (data-only payload)
        |
        +──> Need background processing ──> Silent (data-only payload)

Scenario	Payload Type	Reason
New message alert	Visible	User needs immediate attention
Order status update	Visible	Time-sensitive information
Background sync	Silent	No user interruption needed
Custom notification UI	Silent	Full control over display
Update badge count	Silent	Background processing needed

Extension Strategy (iOS)

When to use Notification Service Extension?

• Need to modify notification content before display
• Need to download and attach media (images, videos)
• Need to decrypt end-to-end encrypted payloads
• Need to add action buttons dynamically

When to use Notification Content Extension?

• Need custom notification UI beyond system template
• Need interactive elements in expanded view

Anti-patterns (NEVER Do)

Permission Handling

NEVER	Why	Instead
Request permission on first launch without context	15-20% acceptance rate	Explain value first, then request
Re-ask after user denies	System ignores repeated requests	Show settings redirect
Ignore provisional authorization	Misses iOS 12+ quiet delivery	Use .provisional option

Token Management

NEVER	Why	Instead
Cache tokens long-term	Tokens can change on reinstall/restore	Always use fresh token from callback
Assume token format	Format varies by platform/SDK	Treat as opaque string
Send token without user association	Can't target notifications	Associate with userId on backend
Store tokens without device ID	Duplicate tokens per user	Use deviceId as unique key

Message Handling

NEVER	Why	Instead
Use notification payload for background processing	onMessageReceived not called in background	Use data-only payload
Rely on silent notifications for time-critical delivery	Delivery not guaranteed	Use visible notifications
Execute heavy operations in background handler	System kills app after ~30 seconds	Queue work, process quickly
Forget to handle both payload types	Missing notifications	Handle notification + data payloads

iOS Specific

NEVER	Why	Instead
Register for notifications before delegate setup	Delegate methods not called	Set delegate before registerForRemoteNotifications()
Skip serviceExtensionTimeWillExpire() implementation	Content modification fails	Always implement fallback
Use .p12 certificates	Expires yearly, deprecated	Use .p8 authentication key

Android Specific

NEVER	Why	Instead
Skip NotificationChannel creation	Notifications don't appear on Android 8.0+	Create channel at app start
Use priority normal for background handlers	Doze mode blocks delivery	Use priority high
Use colored notification icons	Android ignores colors, shows white square	Use white-on-transparent icons

Skill Format

Each rule file follows a hybrid format for fast lookup and deep understanding:

• Quick Pattern: Incorrect/Correct code snippets for immediate pattern matching
• When to Apply: Situations where this rule is relevant
• Deep Dive: Full context with step-by-step guides and platform-specific details
• Common Pitfalls: Common mistakes and how to avoid them
• Related Rules: Cross-references to related patterns

Impact ratings: CRITICAL (fix immediately), HIGH (significant improvement), MEDIUM (worthwhile optimization)

When to Apply

Reference these guidelines when:

• Setting up push notifications in a mobile app
• Debugging push notification delivery issues
• Implementing background notification handlers
• Integrating deep linking with push notifications
• Managing push tokens and device registration
• Troubleshooting platform-specific push issues
• Reviewing push notification code for reliability

Priority-Ordered Guidelines

Priority	Category	Impact	Prefix
1	iOS Setup	CRITICAL	ios-
2	Android Setup	CRITICAL	android-
3	Token Management	HIGH	token-
4	Message Handling	HIGH	message-
5	Deep Linking	MEDIUM	deeplink-
6	Infrastructure	MEDIUM	infra-

Quick Reference

Critical: iOS Setup

Setup checklist:

• Generate APNs authentication key (.p8) from Apple Developer
• Upload to Firebase Console with Key ID and Team ID
• Enable Push Notifications capability in Xcode
• Set UNUserNotificationCenter delegate in didFinishLaunchingWithOptions
• Request notification authorization before registering
• Implement foreground presentation options

Critical: Android Setup

Setup checklist:

• Add google-services.json to app/ directory
• Apply google-services Gradle plugin
• Create NotificationChannel (Android 8.0+)
• Request POST_NOTIFICATIONS permission (Android 13+)
• Implement FirebaseMessagingService
• Set notification icon (transparent background + white)
• Use priority 'high' for Doze mode compatibility

High: Token Management

Token lifecycle:

// 1. Register token with server
const token = await getToken();
await registerToken(token, userId);

// 2. Handle token refresh
onTokenRefresh((newToken) => {
  updateTokenOnServer(newToken, userId);
});

// 3. Handle invalidation
if (error.code === 'DeviceNotRegistered') {
  deleteTokenFromDatabase(token);
}

High: Message Handling

Payload types:

• data-only: Background handler runs on both platforms
• notification + data: iOS/Android behavior differs
  • iOS: Always shows notification
  • Android: Background = system tray, Foreground = onMessageReceived

Priority settings:

• Use priority: 'high' for time-sensitive notifications
• Required for Android Doze mode background handlers

Rules

Full documentation with code examples in rules/:

iOS Setup (ios-*)

File	Impact	Description
ios-apns-auth-key.md	CRITICAL	APNs authentication key setup
ios-delegate-setup.md	CRITICAL	UNUserNotificationCenter delegate configuration
ios-permission-request.md	CRITICAL	Notification permission request flow
ios-token-registration.md	HIGH	APNS token registration and handling
ios-foreground-display.md	HIGH	Display notifications in foreground
ios-method-swizzling.md	MEDIUM	Method Swizzling management
ios-extension-build.md	MEDIUM	Notification Service Extension setup

Android Setup (android-*)

File	Impact	Description
android-notification-channel.md	CRITICAL	Notification channel creation (Android 8.0+)
android-permission.md	CRITICAL	POST_NOTIFICATIONS runtime permission (Android 13+)
android-google-services.md	CRITICAL	Firebase project configuration
android-messaging-service.md	HIGH	FirebaseMessagingService implementation
android-notification-icon.md	MEDIUM	Notification icon asset requirements
android-priority-high.md	HIGH	Priority 'high' for Doze mode

Token Management (token-*)

File	Impact	Description
token-registration.md	HIGH	Token registration with backend
token-refresh.md	HIGH	Token refresh handling
token-invalidation.md	MEDIUM	DeviceNotRegistered error handling

Message Handling (message-*)

File	Impact	Description
message-data-vs-notification.md	CRITICAL	data vs notification payload differences
message-background-handler.md	HIGH	Background message processing
message-foreground-handler.md	HIGH	Foreground notification display

Deep Linking (deeplink-*)

File	Impact	Description
deeplink-navigation-conflict.md	MEDIUM	React Navigation conflict resolution
deeplink-terminated-state.md	MEDIUM	Deep link handling when app is terminated

Infrastructure (infra-*)

File	Impact	Description
infra-firewall-ports.md	MEDIUM	Network firewall configuration
infra-backup-fid.md	MEDIUM	Firebase Installation ID backup exclusion
infra-rate-limiting.md	MEDIUM	Push notification rate limiting

Best Practices

File	Impact	Description
permission-timing.md	HIGH	Permission request timing optimization (70-80% acceptance)
testing-debugging.md	HIGH	Testing tools, debugging techniques, payload validation

Searching Rules

# Find rules by keyword
grep -l "apns" rules/
grep -l "fcm" rules/
grep -l "token" rules/
grep -l "background" rules/
grep -l "permission" rules/
grep -l "deeplink" rules/

Problem → Rule Mapping

Problem	Start With
iOS not receiving push	ios-apns-auth-key → ios-delegate-setup
Android not receiving push	android-google-services → android-notification-channel
Push not working in background	android-priority-high → message-background-handler
Push not visible in foreground	ios-foreground-display or message-foreground-handler
Token missing/expired	token-registration → token-refresh
Deep link conflict error	deeplink-navigation-conflict
Notification icon broken (Android)	android-notification-icon
Failed on corporate network	infra-firewall-ports
Background handler not called (Android)	android-priority-high → message-data-vs-notification
userNotificationCenter not called (iOS)	ios-delegate-setup
404 error after backup restore	infra-backup-fid
Send failed (429 error)	infra-rate-limiting
Low permission acceptance rate	permission-timing → ios-permission-request
How to debug/test push	testing-debugging
Cannot test locally	testing-debugging → ios-apns-auth-key

Platform-Specific Notes

iOS (APNS)

• Requires Apple Developer account and APNs authentication key (.p8)
• Different behavior for Development vs Production builds
• Delegate must be set before other SDK initialization
• Method Swizzling can interfere with delegate calls

Android (FCM)

• Requires google-services.json from Firebase Console
• NotificationChannel required for Android 8.0+
• Runtime permission required for Android 13+
• Doze mode requires priority: 'high' for background handlers
• Notification icons must be monochrome (white on transparent)

React Native

• Common issue: gcm.message_id required for foreground notifications
• Deep linking conflicts with React Navigation
• Terminated state requires native → JS bridge pattern

Expo

• ExpoPushToken format: ExponentPushToken[...]
• Rate limit: 600 push notifications per second per project
• Development builds required for SDK 53+
• Use eas credentials for APNs key management

Full Compiled Document

For the complete guide with all rules expanded: AGENTS.md

Attribution

Based on push notification troubleshooting guides and Firebase Cloud Messaging official documentation.