How i can send notifications when my app is closed in Ionic?

Question

I'm using Ionic for mobile dev, i'm actually using LocalNotifications

Every 5 minutes i check in my server if have new question:

this.checkQuestions();
this.IntervalId = setInterval(() => {
  this.checkQuestions();
}, 300000);

My function checkQuestions() make a for() with the data of my server:

  for (var i = 0; i < res.data.notificar.questions.length; i++) {
    this.localNotifications.schedule({
      id: i, 
      priority: 2,
      text: 'Produto: ' + res.data.notificar.questions[i].produto.substring(0, 20) + '...',
      title: 'Nova pergunta, conta: ' + res.data.notificar.questions[i].conta,
      smallIcon: 'res://notification',
      foreground: true,
    });
  }

The problem is when my app is closed, this logic don't run and my customers don't receive the notifications. There's some alternative in Ionic to send notification when my app is closed?

I need to check every 5 minutes in my server even the app is closed.

Answer 1

If your user kill the app you can not make sure your user keep your app active. But if you really want to try you can use this.

The most efficient is to use Push Notifications. Your server can send notification to your app when new data will be stored.

EDIT

Server side you can run a function to send push notification with something like this :

function sendGCM($message, $id) {


    $url = 'https://fcm.googleapis.com/fcm/send';

    $fields = array (
            'registration_ids' => array (
                    $id
            ),
            'data' => array (
                    "message" => $message
            )
    );
    $fields = json_encode ( $fields );

    $headers = array (
            'Authorization: key=' . "YOUR_KEY_HERE",
            'Content-Type: application/json'
    );

    $ch = curl_init ();
    curl_setopt ( $ch, CURLOPT_URL, $url );
    curl_setopt ( $ch, CURLOPT_POST, true );
    curl_setopt ( $ch, CURLOPT_HTTPHEADER, $headers );
    curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, true );
    curl_setopt ( $ch, CURLOPT_POSTFIELDS, $fields );

    $result = curl_exec ( $ch );
    echo $result;
    curl_close ( $ch );
}

?>

Run this function each 5 minutes in php if you want but better when new data are stored.

SOURCE

And, Ionic side, you can execute a function to get your data when you catch a push notification. Somethink like this :

import { Component } from '@angular/core';
import { Platform } from 'ionic-angular';
import { StatusBar, Splashscreen } from 'ionic-native';

import { HomePage } from '../pages/home/home';
import {
  Push,
  PushToken
} from '@ionic/cloud-angular';

@Component({
  templateUrl: 'app.html'
})
export class MyApp {
  rootPage = HomePage;

  constructor(platform: Platform, public push: Push) {
    platform.ready().then(() => {
      StatusBar.styleDefault();
      Splashscreen.hide();

      this.push.register().then((t: PushToken) => {
        return this.push.saveToken(t);
      }).then((t: PushToken) => {
        console.log('Token saved:', t.token);
      });

      this.push.rx.notification()
      .subscribe((msg) => {
        // CALL SERVE TO GET DATA
      });
    });
  }
}

SOURCE