FCM iOS: Where is the "from" property in the payload?

[pjivers-bom]

I have a background message handler set up like so:

const onMessageReceived = async (message: FirebaseMessagingTypes.RemoteMessage) => {
  if (message.from && message.from.startsWith('/topics/warning')) {
    onWarningMessageReceived(message)
  } else {
    onGenericMessageReceived(message)
  }
}

messaging().setBackgroundMessageHandler(onMessageReceived)

As you can see, it uses the "from" property included in the message to check the topic the message was sent from, and then delegates to a specific handler. This works great on Android, but for some reason the "from" property isn't present when the message is received on iOS.

I can see from the types definition that "from" is optional, but it doesn't explain what circumstances it gets attached to the message. There are other properties such as "contentAvailable" that are iOS-only, but "from" isn't described in that way.

Is there a reason I get this property in a message on Android but not on iOS? I've noticed that "sentTime" and "ttl" are also missing when messages are received on iOS.

[mikehardy]

It appears we would pass it through if it came in:

react-native-firebase/packages/messaging/ios/RNFBMessaging/RNFBMessagingSerializer.m

Lines 64 to 68 in 3b48240

	// message.from
	if ([key isEqualToString:@"from"]) {
	message[@"from"] = userInfo[key];
	continue;
	}

I don't have any solid answers but I'd rummage around in firebase-ios-sdk looking for this:

https://github.com/firebase/firebase-ios-sdk/blob/8b3ee5f12903185411c6cb839341fb34c31e4daa/FirebaseMessaging/Sources/FIRMessagingConstants.m#L19