Migrate to Firebase Installation IDs

If you send push notifications through FCM, register Firebase Installation IDs (FIDs) with Customer.io instead of FCM registration tokens. FID mode is optional, and your existing token-based integration keeps working until you choose to migrate.

If you send push notifications through FCM, Firebase can register devices with Firebase Installation IDs (FIDs) ↗ instead of FCM registration tokens. Starting in version 4.8.0, the Customer.io Flutter SDK registers the FID on each platform where your app turns on FID registration. Until you do, the SDK keeps registering FCM tokens.

When someone opens a version of your app with FID registration turned on, the SDK replaces the device’s FCM token with the FID on their profile. You don’t need to change anything in Customer.io. To learn how FIDs differ from FCM tokens and how Customer.io sends to each, see Device IDs.

Turn on FID mode

1. Update customer_io to 4.8.0 or later. Use firebase-messaging 25.1.2 or later on Android and FirebaseMessaging 12.19.0 or later on iOS. If another package, like firebase_messaging, pins an older Firebase version, update that package too.
2. Turn on FID registration in your native projects. See Firebase’s Android ↗ and Apple ↗ setup guides for details.
   • Android: in android/app/src/main/AndroidManifest.xml, inside <application>:
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     <meta-data
         android:name="firebase_messaging_installation_id_enabled"
         android:value="true" />

   • iOS: in ios/Runner/Info.plist:
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     <key>FirebaseMessagingInstallationIdEnabled</key>
     <true/>

3. If your app forwards Firebase’s registration callbacks to Customer.io in native code, forward the FID callback instead of the token callback. Firebase calls only the FID callback in FID mode.
   • Android: forward onRegistered instead of onNewToken.
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     override fun onRegistered(installationId: String) {
         CustomerIOFirebaseMessagingService.onRegistered(this, installationId)
     }

   • iOS: forward messaging(_:didReceiveRegistration:) instead of messaging(_:didReceiveRegistrationToken:).
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     func messaging(_ messaging: Messaging, didReceiveRegistration installationId: String?) {
         MessagingPush.shared.messaging(messaging, didReceiveRegistration: installationId)
     }

4. If your app calls CustomerIO.instance.registerDeviceToken(), pass the FID instead of an FCM token. You can get it with FirebaseInstallations.instance.getId() from the firebase_app_installations package. Firebase doesn’t return an FCM token in FID mode. Reading the FID doesn’t register it with FCM, so FCM can’t deliver to it until Firebase registers the app. Firebase registers the app at startup by default. If you turned off FCM auto-initialization, call FirebaseMessaging.instance.register() (firebase_messaging 17.0.0 or later) first, and read the FID after it completes.

To go back to FCM tokens, remove the FID setting and forward the token callbacks again.