• Go to the Firebase console
• In the center of the project overview page, click the Android icon or Add app to launch the setup workflow.
• Enter your app's package name in the Android package namefield.
• (Optional) Enter other app information: App nickname and Debug signing certificate SHA-1.
• Click Register app.

• Download and then add the Firebase Android configuration file (google-services.json) to your app:
  • Click Download google-services.json to obtain your Firebase Android config file.
  • Move your config file into the module (app-level) root directory of your app.
• To make the values in your google-services.json config file accessible to Firebase SDKs, you need the Google services Gradle plugin
  • In your root-level (project-level) Gradle file (/build.gradle), add the Google services plugin as a buildscript dependency:

    
    buildscript {
        repositories {
          // Make sure that you have the following two repositories
          google()  // Google's Maven repository
          mavenCentral()  // Maven Central repository
        }
    
        dependencies {
          ...
    
          // Add the dependency for the Google services Gradle plugin
          classpath 'com.google.gms:google-services:4.3.15'
        }
    }
    
    allprojects {
      ...
    
      repositories {
        // Make sure that you have the following two repositories
        google()  // Google's Maven repository
        mavenCentral()  // Maven Central repository
      }
    }
    

  • In your module (app-level) Gradle file (usually //build.gradle), add the Google services plugin:

    
    plugins {
        id 'com.android.application'
    
        // Add the Google services Gradle plugin
        id 'com.google.gms.google-services'
        ...
    }
    

• In your module (app-level) Gradle file (usually //build.gradle), add the dependencies for the Firebase products that you want to use in your app. We recommend using the Firebase Android BoM to control library versioning.

  
  dependencies {
    // Import the Firebase BoM
    implementation platform('com.google.firebase:firebase-bom:31.4.0')
    // When using the BoM, you don't specify versions in Firebase library dependencies
  }
  

  Note: By using the Firebase Android BoM, your app will always use compatible versions of Firebase Android libraries.
• After adding the dependencies for the products you want to use, sync your Android project with Gradle files.

func registerForPushNotifications() {
 open class MyFirebaseMessagingService: FirebaseMessagingService() {

    override fun onNewToken(token: String) {
        super.onNewToken(token)
    }

    override fun onMessageReceived(remoteMessage: RemoteMessage) = Unit
}

open class MyFirebaseMessagingService: FirebaseMessagingService() {
    override fun onNewToken(token: String) {
        super.onNewToken(token)
        setFCMToken(token)
    }
    override fun onMessageReceived(remoteMessage: RemoteMessage) = Unit
}

open class MyFirebaseMessagingService: FirebaseMessagingService() {
    override fun onNewToken(token: String) {
        super.onNewToken(token)
        setFCMToken(token)
    }

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        if (remoteMessage.data.isNotEmpty()) {
            navigateToFCM(remoteMessage.data, this)
        }
    }
}