无法访问IOS回调中来自FCM推送通知的数据

Question

我正在使用Firebase FCM向我的App上的用户发送通知。我可以很好地发送通知，但是当尝试在回调函数中访问通知的数据时，没有任何反应...

这是我的代码：

//Firebase cloud function RTDB Trigger:

exports.cannectionPostNotification = functions.database.ref('/feed/{userId}/{postId}')
.onCreate((snapshot, context) => {
  const userId = context.params.userId;
  const post = snapshot.val();

  const ref = admin.database().ref(`users/${userId}/notificationTokens`);
  return ref.once("value", function(snap){
      const payload = {
            notification: {
                title: `New Post from ${post.username}`,
                body: post.capText,
            },
            data: {
              //need to access this to navigate to 
              //this screen when the notification is open...
              screen: 'imageScreen'
            },
      };

        admin.messaging().sendToDevice(snap.val(), payload)
  }, function (errorObject) {
      console.log("The read failed: " + errorObject.code);
  });
});



//App.js callback..

this.notificationOpenedListener = fire.notifications().onNotificationOpened((notificationOpen) => {
    const { title, body } = notificationOpen.notification;
    const { screen } = notificationOpen.data;
    this.showAlert(title, body);
    //alert won't show when app opens from notifiation...
    alert('NOTIFICATION OPENED' + screen);
});

我的目标是根据有效负载中的数据导航到适当的屏幕，但是我无法从回调中获取任何信息。

我非常感谢我提供的有关此问题的所有指导，

谢谢！