Add notifications to a media app

When building a media app that processes audio or video, it's important to use the correct notifications and notification channels. This ensures that notifications have the following valuable features:

Have notification priority
Are non-dismissable
Use audio attributes for ringtones

Use NotificationChannel.Builder to set up two notification channels: one for incoming calls and the other for active calls.

internal companion object {
    const val TELECOM_NOTIFICATION_ID = 200
    const val TELECOM_NOTIFICATION_ACTION = "telecom_action"
    const val TELECOM_NOTIFICATION_INCOMING_CHANNEL_ID = "telecom_incoming_channel"
    const val TELECOM_NOTIFICATION_ONGOING_CHANNEL_ID = "telecom_ongoing_channel"

    private val ringToneUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE)
}

To display the notification everywhere and allow it to play audio for the ringtone, set the importance of the incoming notification channel to high.

val incomingChannel = NotificationChannelCompat.Builder(
        TELECOM_NOTIFICATION_INCOMING_CHANNEL_ID,
        NotificationManagerCompat.IMPORTANCE_HIGH,
    ).setName("Incoming calls")
        .setDescription("Handles the notifications when receiving a call")
        .setVibrationEnabled(true).setSound(
            ringToneUri,
            AudioAttributes.Builder()
                .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
                .setLegacyStreamType(AudioManager.STREAM_RING)
                .setUsage(AudioAttributes.USAGE_NOTIFICATION_RINGTONE).build(),
        ).build()

Only active calls requires the importance to be set to default. Use the following incoming call style to allow notifications for incoming calls to be non-dismissable.

val ongoingChannel = NotificationChannelCompat.Builder(
        TELECOM_NOTIFICATION_ONGOING_CHANNEL_ID,
        NotificationManagerCompat.IMPORTANCE_DEFAULT,
    )
    .setName("Ongoing calls")
    .setDescription("Displays the ongoing call notifications")
    .build()

To address use cases where the user's device is locked during an incoming call, use a full-screen notification to display an activity to allow the user to answer the call.

// on the notification
val contentIntent = PendingIntent.getActivity(
    /* context = */ context,
    /* requestCode = */ 0,
    /* intent = */ Intent(context, TelecomCallActivity::class.java),
    /* flags = */ PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE,
)

Read Create a call style notification for call apps for instructions on using CallStyle to distinguishing call notifications from other types of notifications.