Push Notifications through Firebase - push-notification

Question

Yesterday Google has announced a new set of tools for Firebase, one of them was Notifications the ability to send notifications from server to devices which are using my app.
But can we now notify users when they receive a new message?
And if not, is there a way around to achieve this?

Answer 1

Looking at the documentation, this doesn't seem currently possible automatically. Here is a possible way to accomplish it "manually" with another server:
Subscribe a user to it's own user ID
In android
FirebaseMessaging.getInstance().subscribeToTopic("InsertUserIDHere");
In IOS
[[FIRMessaging messaging] subscribeToTopic:#"/topics/InsertUserIDHere"];
Setup an outside server that checks every sent messages. When a message is sent, the server should create a notification that includes the recipient's user ID as the topic.
Look here for more info.

Answer 2

You can send messages to group of users (targeting a specific "topic") or to a single device (targeting a Firebase Cloud Messaging token).
To subscribe a device to a topic use:
FirebaseMessaging.getInstance().subscribeToTopic("topicName");
To obtain the device token use (*1) :
FirebaseInstanceId.getInstance().getToken();
Then you can use the Firebase Notificaitons web console, or the FCM server API if you want to send messages from your server.
See: https://firebase.google.com/docs/cloud-messaging/downstream#sending_topic_messages_from_the_server
Notes:
[1] getToken() can return null if the token is not yet available.
You can use the callback onTokenRefresh() to be notified when the token is available and when the token is rotated.
See: https://firebase.google.com/docs/cloud-messaging/android/client#sample-register