Add detailed instruction for creating custom notification channel and how to override it

[ahmedShaheer3]

Hey there i have struggling for hours just know how would i create custome notificatication channel and over ride the default on. The only instruction i find in docs is firebase.json section which is following

https://rnfirebase.io/messaging/usage#firebasejson

under firebase.json section you have mentioned a property
"messaging_android_notification_channel_id": "high-priority"

This is the whole instruction i find in docs which is incomplete you need to edit more detail section like

Adding Custom notification channel

First step:
Edit Main.Activity.java with the following code

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
String channelId = "custom_channel_id"; // Replace with your desired channel ID
String channelName = "custom_channel_name"; // Replace with your desired channel name
int importance = NotificationManager.IMPORTANCE_HIGH;

NotificationChannel channel = new NotificationChannel(channelId, channelName, importance);
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}
Note: Make sure to insert in onCreate function before onCreate() like this

@OverRide
protected void onCreate(Bundle savedInstanceState) {
SplashScreen.show(this, R.style.SplashTheme, true);
// Change the importance level of the default channel (if on Android Oreo or above)
// Create a custom channel with HIGH importance (if on Android Oreo or above)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
String channelId = "custom_channel_id"; // Replace with your desired channel ID
String channelName = "custom_channel_name"; // Replace with your desired channel name
int importance = NotificationManager.IMPORTANCE_HIGH;

NotificationChannel channel = new NotificationChannel(channelId, channelName, importance);
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}
super.onCreate(null);
}

Your are making custom notification channel with priority high so that notification banner will be displayed

Second step:
Create firebase.config on your root folder i.e // /firebase.json (if not exits)

Third step:
paste this code in firebase.json

{
"react-native": {
"messaging_android_notification_channel_id": "custom_channel_id"
}
}

By this you are overriding the default fcm channel .
Note: Make sure the custom_channel_id be same