node-server.js

var admin = require("firebase-admin");
var serviceAccount = require("../controllers/updated_key_iot.json");
admin.initializeApp({credential: admin.credential.cert(serviceAccount),
databaseURL: "https://your-domain.firebaseio.com"});
var registrationToken = "deviceRegisterationToken-generates-from-ios-application";
var payload={ notification:{
title: "Have a great weekend",} };
var options = { priority: "high", 
timeTolive: 60*60*24
};
admin.messaging().sendToDevice(registrationToken, payload, options).then(function(response){
console.log("Succesfully sent Message:",response);}).catch(function(error){ console.log("Error Sending Message:", error);});