Prerequisites
Castled uses Google Firebase Cloud Messaging(FCM) to send push notifications to Android devices. The following steps will walk you through the process of setting up your application to receive push notification from Castled.

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Quick Demo

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Enabling Push Notification in SDK

Set the flag enablePush to true when initializing the SDK 
// SDK initialization
CastledNotifications.initialize(
    this, CastledConfigs.Builder()
        .apiKey("<api-key>")
        .location(<location>)
        .enablePush(true)
        .build()
)

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Permissions

Starting from Android 13 (API level 33), a new runtime permission, POST_NOTIFICATIONS, has been introduced for apps to send non-exempt notifications, including those from Foreground Services (FGS). You need to declare following permissions in the App’s manifest file.
AndroidManifest.xml
<manifest ...>
    <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
    <application ...>
        ...
    </application>
</manifest>
Once the manifest file is updated, app should request the user for the permission at runtime. Here are some guidelines on requesting runtime permissions.

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Firebase push messaging handling service

By default SDK takes care of FCM push token fetch and notification handling once app gets the permission to post notification. In case the app has registered its own Firebase message service class for handling FCM token, SDK needs to be notified of the new token and any push notification received from Castled platform. This can be done as follows: Your app manifest would have a service class similar to MyAppMessagingService to handle Firebase messaging events.
AndroidManifest.xml
<manifest ...>
    ...
    <application ...>

        <service
            android:name="io.castled.android.notifications.push.MyAppMessagingService"
            android:exported="false">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
        ...
    </application>

</manifest>
Add the following code snippets in the overrided onNewToken and onMessageReceived methods of your FCM service class.
MyAppMessagingService.kt
class MyAppMessagingService : FirebaseMessagingService() {
    ...

    override fun onNewToken(token: String) {
        super.onNewToken(token)
        // Notify SDK of new token
        CastledNotifications.onTokenFetch(token, PushTokenType.FCM)

        // Your custom token handling code goes here...
        ...
    }

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        if (CastledNotifications.isCastledPushMessage(remoteMessage)) {
            // Notification initiated from Castled platform. Handle message payload
            CastledNotifications.handlePushNotification(this, remoteMessage)
        } else {
            // Your custom push notification handling code goes here...
            ...
        }
    }
}

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Notification default configs

SDK provides option to specify default values for some of the push notification payload fields. You need to create a castled.xml file in the res/values folder of your app project. Default values takes effect only if push payload doesn’t have any values specified for these fields.

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Notification channels

Add the following values to castled.xml if you want to specify a default channel for notifications from Castled. More details on android notifications channels can be found here.
castled.xml
<resources>
    ...

    <string name="io_castled_push_default_channel_id">YOUR_NOTIFICATION_CHANNEL_ID</string>
    <string name="io_castled_push_default_channel_name">YOUR_NOTIFICATION_CHANNEL_NAME</string>
    <string name="io_castled_push_default_channel_desc">YOUR_NOTIFICATION_CHANNEL_DESC</string>
    <integer name="io_castled_push_default_channel_importance">YOUR_NOTIFICATION_CHANNEL_IMPORTANCE_VALUE</integer>

    ...
</resources>
YOUR_NOTIFICATION_CHANNEL_IMPORTANCE_VALUE can be any integer in the range [1,4], 1 being lowest importance and 5 being highest.

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Small and large default icons

You can also optionally specify default small and large icons for push notifications in castled.xml.

1. small icon 2. large icon

castled.xml
<resources>
    ...

    <!-- Castled default small and large icons -->
    <drawable name="io_castled_push_default_small_icon">YOUR_NOTIFICATION_SMALL_ICON</drawable>
    <drawable name="io_castled_push_default_large_icon">YOUR_NOTIFICATION_LARGE_ICON</drawable>

    ...
</resources>

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Notification Listeners

App can listen to Castled push notification events by registering a listener. Listener object should implement the interface CastledPushNotificationListener. Following code snippet uses an anonymous object as the listener.
MyApplicationClass.kt
    // Listening to push notification events
    CastledNotifications.subscribeToPushNotificationEvents(object :
        CastledPushNotificationListener {

        // Push received
        override fun onCastledPushReceived(pushMessage: CastledPushMessage) {
            logger.debug("Received push message with id: ${pushMessage.getNotificationDisplayId()}")
        }

        // Push clicked
        override fun onCastledPushClicked(
            pushMessage: CastledPushMessage,
            actionContext: CastledActionContext
        ) {
            logger.debug("User clicked push message with id: ${pushMessage.getNotificationDisplayId()}")
        }

        // Push dismissed
        override fun onCastledPushDismissed(pushMessage: CastledPushMessage) {
            logger.debug("Dismissed push message with id: ${pushMessage.getNotificationDisplayId()}")
        }
    })

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FAQ