Push notifications (expo-notifications) in React Native - Build, Publish & Deploy

Build & Publish - Push notifications (expo-notifications)

Performance Impact

Push notifications have minimal impact on app frame rate and UI smoothness because they are handled by the system in the background. However, frequent or heavy notifications can increase battery usage and network data consumption. Memory usage is low since notifications do not run heavy code unless the app is opened from them.

Optimization Tips

To keep your app responsive at 60fps, avoid processing heavy tasks directly in notification handlers. Use lightweight data payloads and defer complex work until the app is active. Use expo-notifications APIs efficiently by registering listeners only when needed and removing them properly to prevent memory leaks.

App Size and Startup Time

Adding expo-notifications increases your app bundle size moderately due to native modules for iOS and Android. This can add a few megabytes but is generally acceptable. Startup time is not affected significantly because notification handling runs outside the main UI thread until the app is launched.

iOS vs Android Differences

On iOS, users must grant explicit permission for notifications, and the system controls notification appearance strictly. Background notification handling is limited. Android allows more customization and background processing with fewer restrictions. Token registration and push service setup differ: iOS uses APNs, Android uses Firebase Cloud Messaging (FCM).

Store Review Guidelines

• iOS App Store requires you to request user permission clearly before sending notifications (Apple Human Interface Guidelines).
• Provide a clear purpose for notifications in your app description and privacy policy.
• Do not send spam or irrelevant notifications; this can lead to app rejection.
• Android Google Play requires proper use of notification channels and respecting user settings.
• Ensure your app handles notification permissions gracefully and does not crash if denied.

Self-Check Question

Your app takes 5 seconds to load this screen after tapping a notification. What is likely wrong?

Answer: The notification handler is doing heavy work on the main thread or blocking startup. Optimize by deferring processing until after the UI loads and keep notification payloads small.

Key Result

Using expo-notifications enables reliable push notifications with minimal UI performance impact, but requires careful permission handling and lightweight notification processing to maintain smooth app experience and meet store guidelines.

Practice

1. What is the main purpose of using expo-notifications in a React Native app?

easy

A. To create animations for app screens

B. To send and receive push notifications to keep users informed

C. To manage app navigation between screens

D. To handle user authentication and login

Solution

1. Step 1: Understand the role of expo-notifications

   The expo-notifications library is designed to handle push notifications in React Native apps.

2. Step 2: Identify the correct purpose

   It allows apps to send and receive notifications, keeping users informed even when the app is closed.

3. Final Answer:

   To send and receive push notifications to keep users informed -> Option B

4. Quick Check:

   expo-notifications = Push notifications [OK]

Hint: Remember: expo-notifications is for alerts, not UI or auth [OK]

Common Mistakes:

• Confusing notifications with navigation or animations
• Thinking expo-notifications manages user login
• Assuming it handles UI styling

2. Which of the following is the correct way to request notification permissions using expo-notifications?

easy

A. await Notifications.requestPermissionsAsync();

B. Notifications.getPermissions();

C. await Notifications.askForPermissions();

D. Notifications.permissionRequest();

Solution

1. Step 1: Recall the correct method name

   The official method to request permissions is requestPermissionsAsync() from expo-notifications.

2. Step 2: Check syntax correctness

   The method is asynchronous and should be awaited: await Notifications.requestPermissionsAsync();

3. Final Answer:

   await Notifications.requestPermissionsAsync(); -> Option A

4. Quick Check:

   Permission request method = requestPermissionsAsync [OK]

Hint: Look for async method starting with 'request' [OK]

Common Mistakes:

• Using non-existent methods like getPermissions or askForPermissions
• Forgetting to await the async call
• Using incorrect method names

3. Given the code snippet below, what will be logged when a notification is received?

import * as Notifications from 'expo-notifications';

Notifications.addNotificationReceivedListener(notification => {
  console.log(notification.request.content.title);
});

// Assume a notification with title 'Hello User' arrives

medium

A. undefined

B. notification

C. Hello User

D. Error: notification is not defined

Solution

1. Step 1: Understand the listener callback

   The listener receives a notification object, and logs notification.request.content.title.

2. Step 2: Match the notification content

   The notification has a title 'Hello User', so that string will be logged.

3. Final Answer:

   Hello User -> Option C

4. Quick Check:

   Logged title = 'Hello User' [OK]

Hint: Listener logs notification title property [OK]

Common Mistakes:

• Expecting the whole notification object to be logged
• Confusing property names or missing nested fields
• Assuming undefined if not familiar with notification structure

4. What is wrong with this code snippet for getting the push token?

import * as Notifications from 'expo-notifications';

const getToken = async () => {
  const token = Notifications.getExpoPushTokenAsync();
  console.log(token);
};

getToken();

medium

A. Missing await before Notifications.getExpoPushTokenAsync()

B. Wrong import statement for Notifications

C. console.log should be inside a .then() block

D. getToken function should not be async

Solution

1. Step 1: Identify async function usage

   The method getExpoPushTokenAsync() returns a Promise and must be awaited.

2. Step 2: Check the code for await

   The code calls Notifications.getExpoPushTokenAsync() without await, so token is a Promise, not the actual token.

3. Final Answer:

   Missing await before Notifications.getExpoPushTokenAsync() -> Option A

4. Quick Check:

   Async calls need await to get result [OK]

Hint: Always await async calls to get actual values [OK]

Common Mistakes:

• Forgetting to await async functions
• Misunderstanding Promises vs values
• Incorrect import statements
• Logging before Promise resolves

5. You want to send a push notification only when the user has granted permission. Which sequence of steps correctly implements this using expo-notifications?

hard

A. Send notification directly without requesting permission or token

B. Get token first with getExpoPushTokenAsync(), then request permission with requestPermissionsAsync()

C. Only request permission and send notification without getting token

D. Request permission with requestPermissionsAsync(), check status, then get token with getExpoPushTokenAsync() if granted

Solution

1. Step 1: Request notification permission

   Use requestPermissionsAsync() to ask the user for permission and check the returned status.

2. Step 2: Get push token if permission granted

   If permission is granted, call getExpoPushTokenAsync() to get the device token for sending notifications.

3. Step 3: Send notification using the token

   Use the token to send push notifications from your server or app.

4. Final Answer:

   Request permission with requestPermissionsAsync(), check status, then get token with getExpoPushTokenAsync() if granted -> Option D

5. Quick Check:

   Permission first, then token, then send [OK]

Hint: Always request permission before getting token [OK]

Common Mistakes:

• Getting token before permission
• Sending notifications without token
• Skipping permission check
• Assuming permission is granted by default