如何处理点击推送通知（Firebase Cloud Messaging）？

Question

Firebase Cloud Messaging sends pushes to my app. And they appear in the system tray when the app is closed.

The task is to open the app and perform some action (like open another fragment for example) when user clicks on the push notification in the tray.

The problem is I don't know how to override the default behaviour when user clicks on the push notification. Is there some kind of callback, broadcast receiver etc?

My FirebaseMessagingService

class FCMHandlerService : FirebaseMessagingService() {

    private val intercomPushClient = IntercomPushClient()

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        logd("onMessageReceived $remoteMessage")
        val notification = remoteMessage.notification ?: return
        logd("Remote message body${notification.body} channel id${notification.channelId} message id${remoteMessage.messageId}")
        
        //you can create here your custom notification when the app receives push being foreground
    }

    override fun onNewToken(token: String) {
        super.onNewToken(token)
        logd("onNewToken $token")
        instance.sendFirebasePushRegistrationToken(token)
    }
}

Service in manifest

        <service
            android:name=".old.push.FCMHandlerService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>

Answer 1

First, it's important to understand that application handles push notification in two different ways depending on wether the app is in the foreground or background .

Notification messages delivered when your app is in the background. In this case, the notification is delivered to the device's system tray. A user tap on a notification opens the app launcher by default.

Messages with both notification and data payload, when received in the background. In this case, the notification is delivered to the device's system tray, and the data payload is delivered in the extras of the intent of your launcher Activity.

Solution when app is in the background

In that case when user clicks on the push notification in the system tray, the app is opened by default. AND you'll get all needed data from the intent.extras . So basically in your main activity onCreate you can simply get extras from intent and perform some action depending on the data, like open some screen.

Important, onMessageReceived method in your FirebaseMessagingService won't be called in this case. You may find misleading info in the inte.net about it, but I suppose the behaviour was different in the past.

Solution when app is in the foreground

The default behaviour is that the push notification doesn't appear in the system tray when the app is opened. But you can create your own FirebaseMessagingService and receive notification info in the mo onMessageReceived .

You can show your custom Notification with PendingIntent. In the PendingIntent you can put activity that must be opened with needed data. Then when user click on the notification the activity with data will be opened.

Again you'll get all needed data in the intent.extras . So basically in your main activity onCreate you can simply get extras from intent and perform some action depending on the data, like open some screen.