Does FCM Messaging for IOS works with Data Messages (app in background)?

[flutter2k20]

Hi There,

I have an IOS app setup to receive FCM push messages. I can receive "notification" messages fine - always shows a notification with the title/body etc.

Now I am trying to send data messages to the app and expecting the

override func application(_ application: UIApplication,
                              didReceiveRemoteNotification userInfo: [AnyHashable : Any],
                              fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void

to be called with the data received. And it never gets called even the app is in foreground. My message/payload looks like

{
  "to": "DEVICE_TOKEN",
  "content_available": true,
  "apns-priority": 5,
  "data": {
    "somekey": "somevalue"
  }
}

I have tried with method swizzling flag enabled or disabled and it does not makes any difference.

My question is, does firebase SDK for IOS support data messages at all?

Thanks!