Скачать или смотреть Solving the iOS FCM Token Length 163 Problem: Ensuring Firebase Notifications Arrive on All Devices

Discover how to resolve the issue of Firebase notifications not arriving on iOS devices with FCM token length 163. This guide provides a comprehensive solution for React Native apps.
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The Dilemma of Firebase Notifications on iOS Devices

If you're working with React Native and using Firebase Cloud Messaging (FCM) for push notifications, you might face a frustrating issue: notifications not arriving on iOS devices with longer FCM tokens. This problem is particularly evident when your devices generate tokens of varying lengths—specifically, those with a length of 163. While notifications may work flawlessly on Android devices and on some iOS devices with shorter tokens, you may still find yourself puzzled by the UNREGISTERED error message: "Requested entity was not found."

In this guide, we will uncover the reasons behind this problem and break down a solution that has already worked for others in the developer community.

Understanding FCM Token Generation

When your React Native application registers for push notifications, Firebase generates an FCM token that uniquely identifies the device to the backend. However, differences in token length can lead to unexpected behavior, particularly on iOS devices under certain configurations. For example:

Android Tokens: Generated token length is typically 152 characters.

iOS Tokens: Inconsistent lengths; some devices generated tokens of 152 characters, while others produced tokens with a length of 163.

It’s worth noting that such discrepancies can affect your ability to send notifications successfully, leading to failure messages when attempting to deliver updates to devices with longer tokens.

The Technical Hurdle

After implementing the proper configurations in Xcode, and even confirming that push notifications capabilities were well-set up, your journey may still lead to an unwelcome impasse. Some surprising outcomes include:

Expected: Notifications should be arriving on all devices (iOS and Android).

Actual Result: While notifications are consistently received on Android and on some iOS devices, they fail to show up in devices that register a longer FCM token.

Key Indicators

iOS Version: Check the iOS version, which might be 13.5.1, as compatibility issues can be a factor.

React Native and Libraries Version: Your in-use libraries must be compatible with Firebase. For instance:

"react-native-firebase": "^5.6.0"

Dependencies in Podfile and build.gradle must be up-to-date and correctly configured.

The Solution that Worked

After delving into potential solutions, the resolution to the FCM token issue was discovered by adjusting how the FCM token was obtained. The initial approach involved using NativeManager to fetch the token, which only returned the first token generated, leading to inconsistencies.

Improved Method

Instead of using:

[[See Video to Reveal this Text or Code Snippet]]

Switch to the following method that leverages the Firebase messaging library directly:

[[See Video to Reveal this Text or Code Snippet]]

This revised code accomplishes two important tasks:

Get Initial Token: It retrieves the first FCM token as expected.

Updates with New Token: Following that, it correctly captures any new tokens generated, particularly the one that should be used for sending notifications.

This transition effectively resolves the issue, allowing notifications to be sent and received on all devices—regardless of the token length.

Final Thoughts

If you're plagued by issues with Firebase notifications on iOS devices that generate longer FCM tokens, revising your token retrieval process can make all the difference. We hope this guide helps you navigate the complexities of push notifications, ensuring that your users stay connected and updated without interruptions. Happy coding!