Unable to get IOS background messaging working

[ak-cloud]

I am trying to implement data fetch in the background for both IOS and Android. While I was able to achieve it on Android but unable to on IOS. Notification in general is working fine. But background messages are only delivered when app comes in foreground. Alerts are working fine in any state. Here is my configuration:

` @OverRide
Future registerNotificationsForUser(String currentUserId) {
firebaseMessaging.requestNotificationPermissions(
const IosNotificationSettings(sound: true, badge: true, alert: true, provisional: false));
firebaseMessaging.onIosSettingsRegistered
.listen((IosNotificationSettings settings) {
print("Settings registered: $settings");
});

firebaseMessaging.configure(onMessage: (Map<String, dynamic> message) {
  print('onMessage : $message');
  var data;
  print(message.runtimeType);
  if(Platform.isIOS){
    data=message;
  }else{
    data=message['data'];
  }


  _doSomethingWithData();

  _showNotification(message['notification'], chatGroupId);
  return;
}, onResume: (Map<String, dynamic> message) {
  print('onResume: $message');
  var data;
  print(message.runtimeType);
  if(Platform.isIOS){
    data=message;
  }else{
    data=message['data'];
  }
  _doSomethingWithData();
  return;
}, onLaunch: (Map<String, dynamic> message) {
  print('onLaunch: $message');
  Map<String, dynamic> data;
  if(Platform.isIOS){
    data=message;
  }else{
    data=message['data'];
  }

     _doSomethingWithData();

  return;
},  onBackgroundMessage: Platform.isIOS ? null :myBackgroundMessageHandler);

`

Here is my payload for background fetch message:

{displayNameTo: someName, category: NEW_MESSAGE_CATEGORY, displayNameFrom: somaName, idTo: someId, idFrom: someId, type: someTYPE, gcm.message_id: 1611893552150294, content-available: 1.0, click_action: FLUTTER_NOTIFICATION_CLICK, aps: {content-available: 1.0}, contentAvailable: true}

Any help will be much appreciated as I have literally read everything internet has to offer. My native IOS app in Swift has similar functions and that works like a charm