Android custom layout for push notification view

notification_layout.xml, the layout to be used for the push notification view.

Inflate the push notification layout using RemoteViews and build the notification.

val contentView = RemoteViews(packageName, R.layout.notification_layout)

val mBuilder = NotificationCompat.Builder(this)
        .setSmallIcon(R.mipmap.ic_launcher)
        .setContentTitle("collapsed title")
        .setContentText("collapsed text")
        .setCustomBigContentView(contentView)

val notification = mBuilder.build()
val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.notify(1, notification)

Complete example in Github