Handler

 class GcmMessageHandler : IntentService("GcmMessageHandler") {

    var mes: String? = null
    private var handler: Handler? = null

    override fun onCreate() {
        super.onCreate()
        handler = Handler()
    }

    override fun onHandleIntent(intent: Intent) {
        val extras = intent.extras
        val gcm = GoogleCloudMessaging.getInstance(this)
        // The getMessageType() intent parameter must be the intent you received
        // in your BroadcastReceiver.
        val messageType = gcm.getMessageType(intent)

        mes = extras.getString("title")
        // showToast();
        if (mes != null) {
            if(extras.getString("category")!=null && extras.getString("category").equals("work",true)) {
                if(!extras.getBoolean("urgently"))
                  mes = "Работа: ${extras.getString("title")}"
                else mes = "Работа (срочно): ${extras.getString("title")}"
            } else if (extras.getString("category")!=null && extras.getString("category").equals("ads",true)){
                if(extras.getString("subcategory")!=null && extras.getString("subcategory").equals("svady",true)){
                    // some handler here
                }
            }
            showNotification(mes!!, extras.getString("message"),extras.getString("category") ?: "",extras.getString("link") ?: "")
            Log.i("GCM", "Received : ($messageType) ${extras.getString("title")} ${extras.getString("message")} category:${extras.getString("category")}")
        }

        GcmBroadcastReceiver.completeWakefulIntent(intent)

    }

     fun showNotification(title: String, message: String,category: String?, link: String?) {
        val mBuilder = NotificationCompat.Builder(this).setSmallIcon(R.mipmap.ic_launcher).setContentTitle(title).setContentText(message)

        val resultIntent = intentFor<MainActivity>()
        resultIntent.putExtra("openNotifications", true)
        resultIntent.putExtra("category",category)
        resultIntent.putExtra("link",link)

        val resultPendingIntent = PendingIntent.getActivity(this, 0, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT)
        mBuilder.setContentIntent(resultPendingIntent)
        mBuilder.setAutoCancel(true)

        val random = Random()
        val mNotificationId = random.nextInt(9999-1000)+1000

        notificationManager.notify(mNotificationId, mBuilder.build())
    }
}