Connection and unknown errors in FlutterFire Messaging (iOS Only)

Question

I implemented FlutterFire Messaging with the subscribeToTopic method, as the snippet below:

final _topics = ['topicName'];

Future<void> subscribeTopics() async {
  for (final topic in _topics) {
    await FirebaseMessaging.instance.subscribeToTopic(topic);
  }
}

Future<void> unsubscribeTopics() async {
  for (final topic in _topics) {
    await FirebaseMessaging.instance.unsubscribeFromTopic(topic);
  }
}

And everything is fine in debug mode, but in my Crashlytics I'm receiving some reports about it (iOS only):

• [firebase_messaging/unknown] The request timed out
• [firebase_messaging/unknown] An unknown error has occurred
• [firebase_messaging/unknown] A data connection is not currently allowed
• [firebase_messaging/unknown] The Inte.net connection appears to be offline

All the errors appears to be about inte.net connection, so my question is: "Should I validate the user connection before use FCM or the lib is ready to deal with it but only in Android?"

Crashlytics Stacktrace

Non-fatal Exception: FlutterError
0  ???                            0x0 MethodChannelFirebaseMessaging.subscribeToTopic + 368 (method_channel_messaging.dart:368)
1  ???                            0x0 Messaging.subscribeTopics + 40 (messaging.dart:40)
2  ???                            0x0 Messaging.observeMessaging + 22 (messaging.dart:22)

Answer 1

It's a general error so you shouldn't worry about it. When the inte.net connection restores the method will hopefully restart itself. You should also consider the case that It might generate an error while the app is in the background.

You can use try catch block to avoid these messages in your crashlytics dashboard.

final _topics = ['topicName'];

Future<void> subscribeTopics() async {
  try {
    for (final topic in _topics) {
      await FirebaseMessaging.instance.subscribeToTopic(topic);
    }
  } on FirebaseException {
    // do nothing
  }
}

Future<void> unsubscribeTopics() async {
  try {
    for (final topic in _topics) {
      await FirebaseMessaging.instance.unsubscribeFromTopic(topic);
    }
  } on FirebaseException {
    // do nothing
  }
}

Note It will also ignore all other error messages too. In that case You can handle it otherwise

final _topics = ['topicName'];

Future<void> subscribeTopics() async {
  try {
    for (final topic in _topics) {
      await FirebaseMessaging.instance.subscribeToTopic(topic);
    }
  } on FirebaseException catch (e) {
    if (e.code == 'unknown') {
      // do nothing
    } else {
      // do something
    }
  }
}

Future<void> unsubscribeTopics() async {
  try {
    for (final topic in _topics) {
      await FirebaseMessaging.instance.unsubscribeFromTopic(topic);
    }
  } on FirebaseException catch (e) {
    if (e.code == 'unknown') {
      // do nothing
    } else {
      // do something
    }
  }
}