Implementing Push Notifications in Ionic with Capacitor

Push notifications are a powerful way to engage users and inform them about updates, messages, and important events in your Ionic app. In this blog, we'll explore how to implement push notifications in an Ionic app using Capacitor, a modern framework for building cross-platform apps.

What are Push Notifications?

Push notifications are messages sent from a server to a user's device. They can alert users about new content, reminders, promotions, or other relevant information. Implementing push notifications in your Ionic app can greatly enhance user engagement and retention.

Prerequisites :

Before we dive into the implementation, make sure you have the following:

An Ionic app set up on your development environment.
The capacitor installed in your Ionic project (npm install @capacitor/core @capacitor/cli).
Access to a push notification service provider (e.g., Firebase Cloud Messaging, OneSignal).

Prepare an Ionic Capacitor App

If you have an existing Ionic app, skip this section. If not, let's create an Ionic app first.

In your preferred terminal, install the latest version of the Ionic CLI:

npm install -g @ionic/cli

Next, let's use the CLI to create a new Ionic Angular app based on the blank starter project and call it capApp:

ionic start capApp blank --type=angular

On the prompt asking to integrate your new app with Capacitor, type y , and press enter. That will add the Capacitor and the Capacitor CLI to our new application.

Once the application has been created successfully, switch to the newly created project directory:

cd capApp/

Finish up by running, which will allow us to fill out our app information.

npx cap init
? App name: CapApp
? App Package ID: com.mydomain.myappname

Building the App & Adding Platforms

Before adding any native platforms to this project, the app must be built at least once. A web build creates the web assets directory that the Capacitor needs (www folder in Ionic Angular projects).

ionic build

Next, let's add the iOS and Android platforms to our app.

npx cap add ios
npx cap add android

Upon running these commands, both android and ios folders at the root of the project are created. These are entirely separate native project artifacts that should be considered part of your Ionic app (i.e., check them into source control).

Using the Capacitor Push Notification API

First of all, we need to install the Capacitor Push Notifications Plugin

npm install @capacitor/push-notifications
npx cap sync

Then, before we get to Firebase, we'll need to ensure that our application can register for push notifications by making use of the Capacitor Push Notification API. We'll also add an alert (you could use console.log statements instead) to show us the payload for a notification when it arrives and the app is open on our device.

In your app, head to the home.page.ts file and add an import statement and a const to make use of the Capacitor Push API:

import {
  ActionPerformed,
  PushNotificationSchema,
  PushNotifications,
  Token,
} from '@capacitor/push-notifications';

Then, add the ngOnInit() method with some API methods to register and monitor for push notifications. We will also add an alert() a few of the events to monitor what is happening:

export class HomePage implements OnInit {

ngOnInit() {
    console.log('Initializing HomePage');

    // Request permission to use push notifications
    // iOS will prompt user and return if they granted permission or not
    // Android will just grant without prompting
    PushNotifications.requestPermissions().then(result => {
      if (result.receive === 'granted') {
        // Register with Apple / Google to receive push via APNS/FCM
        PushNotifications.register();
      } else {
        // Show some error
      }
    });

    // On success, we should be able to receive notifications
    PushNotifications.addListener('registration',
      (token: Token) => {
        alert('Push registration success, token: ' + token.value);
      }
    );

    // Some issue with our setup and push will not work
    PushNotifications.addListener('registrationError',
      (error: any) => {
        alert('Error on registration: ' + JSON.stringify(error));
      }
    );

    // Show us the notification payload if the app is open on our device
    PushNotifications.addListener('pushNotificationReceived',
      (notification: PushNotificationSchema) => {
        alert('Push received: ' + JSON.stringify(notification));
      }
    );

    // Method called when tapping on a notification
    PushNotifications.addListener('pushNotificationActionPerformed',
      (notification: ActionPerformed) => {
        alert('Push action performed: ' + JSON.stringify(notification));
      }
    );
}

Here is the full implementation of home.page.ts:

import { Component, OnInit } from '@angular/core';

import {
  ActionPerformed,
  PushNotificationSchema,
  PushNotifications,
  Token,
} from '@capacitor/push-notifications';

@Component({
  selector: 'app-home',
  templateUrl: 'home.page.html',
  styleUrls: ['home.page.scss'],
})
export class HomePage implements OnInit {
  ngOnInit() {
    console.log('Initializing HomePage');

    // Request permission to use push notifications
    // iOS will prompt user and return if they granted permission or not
    // Android will just grant without prompting
    PushNotifications.requestPermissions().then(result => {
      if (result.receive === 'granted') {
        // Register with Apple / Google to receive push via APNS/FCM
        PushNotifications.register();
      } else {
        // Show some error
      }
    });

    PushNotifications.addListener('registration', (token: Token) => {
      alert('Push registration success, token: ' + token.value);
    });

    PushNotifications.addListener('registrationError', (error: any) => {
      alert('Error on registration: ' + JSON.stringify(error));
    });

    PushNotifications.addListener(
      'pushNotificationReceived',
      (notification: PushNotificationSchema) => {
        alert('Push received: ' + JSON.stringify(notification));
      },
    );

    PushNotifications.addListener(
      'pushNotificationActionPerformed',
      (notification: ActionPerformed) => {
        alert('Push action performed: ' + JSON.stringify(notification));
      },
    );
  }
}

After this, you'll want to generate a new build and let Capacitor know about the changes. You can do that with:

ionic build
npx cap copy

Creating a Project for Your App on Firebase

Before we can connect Firebase Cloud Messaging to your application and send push notifications, you'll need to start a project in Firebase.

Go to the Firebase Console and click the Add Project button.

Name the project, accept the Firebase ToS, and click Create project to continue. A Project ID should be automatically generated for you.

Android

Integrating Firebase with the Android app

This section more-or-less mirrors the setting up of Firebase using the Firebase console documentation. See below for specific Capacitor-related notes.

Go to the Project Overview page for your Firebase project and at the top, click on the Android icon to add a new Android application.

The next screen will ask you for some information about your application.

Your Android package name should match the appId from your capacitor.config.json file
We used com.mydomain.myappname for this Capacitor app ID, so that is what we'll use for this entry.
Nickname and Debug Signing Certificate are optional

Then click the Register app button.

Download and Use the`google-services.json` file

The next prompt will ask you to download a google-services.json file. This file contains the information your Capacitor app needs to connect to Firebase from Android.

Download the google-services.json file to your local machine. Then move the file into your Capacitor Android project directory, specifically under android/app/.

We don't need to add any dependencies to our project because Capacitor projects automatically include a version of firebase-messaging in it's build.gradle files.

iOS

Prerequisites

iOS push notifications are significantly more complicated to set up than Android. You must have a paid Apple Developer accountand take care of the following items before being able to test push notifications with your iOS application:

Setup the proper Development or Production certificates & provisioning profiles for your iOS application in the Apple Developer Portal
Create an APNS certificate or keyfor either Development or Production in the Apple Developer Portal
Ensure Push Notification capabilities have been enabled in your application in Xcode
Have a physical iOS device as per the guidelines in the Environment Setup documentation

Integrating Firebase with our native iOS app

This part is very similar to the Android section above, with a few key differences.

First, go to the Project Overview page for your Firebase project. If you've been following this guide, you'll already have an Android application listed at the top of the page.

To add iOS to your Firebase project, click the Add App button and select the iOS platform.

The next screen will ask you for some information about your application.

Your iOS bundle ID should match the appId from your capacitor.config.json file
We used com.mydomain.myappname for this Capacitor app ID, so that is what we'll use for this entry.
App Nickname and App Store ID are optional

Then click the Register app button.

Add the`GoogleService-Info.plist` file to your iOS app

Note: This isnotthe same file used for your Android app.

Download the GoogleService-Info.plist provided to your local machine.

You'll then want to open Xcode...

npx cap open ios

... and move the .plist file into your Xcode project as instructed by Firebase, ensuring to add it to all targets.

Add the Firebase SDK via CocoaPods

The Push Notification API on iOS makes use of CocoaPods - an iOS dependency management system - and we need to tell CocoaPods to make use of Firebase.

To do this, we need to modify the Podfile, which can be found in Xcode under Pods:

We need to add Firebase to the CocoaPods provided for our App target. To do that, add pod Firebase/Messaging to your target 'App' section, like so:

target 'App' do
  capacitor_pods
  # Add your Pods here
  pod 'Firebase/Messaging' # Add this line
end

Your Podfile should look something like this:

require_relative '../../node_modules/@capacitor/ios/scripts/pods_helpers'

platform :ios, '13.0'
use_frameworks!

# workaround to avoid Xcode caching of Pods that requires
# Product -> Clean Build Folder after new Cordova plugins installed
# Requires CocoaPods 1.6 or newer
install! 'cocoapods', :disable_input_output_paths => true

def capacitor_pods
  pod 'Capacitor', :path => '../../node_modules/@capacitor/ios'
  pod 'CapacitorCordova', :path => '../../node_modules/@capacitor/ios'
end

target 'App' do
  capacitor_pods
  # Add your Pods here
  pod 'Firebase/Messaging'
end

post_install do |installer|
  assertDeploymentTarget(installer)
end

Update the Project

Now we'll need to ensure that our iOS project is updated with the proper Firebase CocoaPod installed.

Note: This part can take a while as CocoaPods needs to download all the appropriate files/dependencies.

npx cap update ios

Add Initialization Code

To connect to Firebase when your iOS app starts up, you need to add the following to your AppDelegate.swift file.

First, add an import at the top of the file:

import Firebase

... and then add the configuration method for Firebase to initialization code to your AppDelegate.swift file, in the application(didFinishLaunchingWithOptions) method.

FirebaseApp.configure()

Then you need to add the following two methods to correctly handle the push registration events:

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
  Messaging.messaging().apnsToken = deviceToken
  Messaging.messaging().token(completion: { (token, error) in
    if let error = error {
        NotificationCenter.default.post(name: .capacitorDidFailToRegisterForRemoteNotifications, object: error)
    } else if let token = token {
        NotificationCenter.default.post(name: .capacitorDidRegisterForRemoteNotifications, object: token)
    }
  })
}

func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
  NotificationCenter.default.post(name: .capacitorDidFailToRegisterForRemoteNotifications, object: error)
}

You're completed AppDelegate.swift file should look something like this:

import UIKit
import Capacitor
import Firebase

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

  var window: UIWindow?


  func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    FirebaseApp.configure()
    return true
  }

  func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    Messaging.messaging().apnsToken = deviceToken
    Messaging.messaging().token(completion: { (token, error) in
      if let error = error {
          NotificationCenter.default.post(name: .capacitorDidFailToRegisterForRemoteNotifications, object: error)
      } else if let token = token {
          NotificationCenter.default.post(name: .capacitorDidRegisterForRemoteNotifications, object: token)
      }
    })
  }

  func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
    NotificationCenter.default.post(name: .capacitorDidFailToRegisterForRemoteNotifications, object: error)
  }

Upload the APNS Certificate or Key to Firebase

If you followed the instructions from the beginning, you'll have created an Apple APNS Certificate or an APNS Auth Key in the Apple Developer portal. You need to upload one of these to Firebase before Firebase can talk to APNS and send push notifications to your application.

To upload your certificate or auth key, from the Project Overview page:

Click on your iOS application and then the Settings gear icon.
On the Settings page, click on the Cloud Messaging tab.
Under the iOS app configuration header, upload your Auth Key or Certificate(s) using the provided Upload button.

Sending a Test Notification

Now for the fun part - let's verify that push notifications from Firebase are working on Android and iOS!

We need to fire up our application on Android or iOS so that our home.page.ts page can register and receive notifications.

To open your Android project in Android Studio:

npx cap open android

To open your iOS project in Xcode:

npx cap open ios

Once the project is open, side-load the application on your device using the Run feature of either Android Studio or Xcode. The app should start up on the home page.

Note: On iOS, you will see a popup asking you to allow notifications for your app - make sure you choose to**Allow notifications*!*

If your app successfully registers and you follow the code above, you should see an alert with a success message!

Now we'll test to see if the notifications are received by our device. To send a notification, in Firebase, go to the Cloud Messaging section under the Grow header in the project pane.

Next, select the New Notification button.

When creating the notification, you only need to specify the following information:

The text of the notification
The title (Android only, optional for iOS)
The Target (either a user segment or topic; I recommend just targeting the iOS or Android app itself, see below)

The Scheduling (leave this to "Now")

At that point, you can review the notification you've put together and select Publish to send the notification out.

If you've set up your application correctly, you'll see an alert pop up on your home screen with the push notification you composed in Firebase. You can then tap on the notification and you should get an alert for the pushActionPerformed event, per our code above.

You can send test notifications from the Firebase console or using the Firebase Cloud Messaging API. Make sure to target the FCM token obtained in Step 4 for your test notifications.

Conclusion

Integrating push notifications using Firebase Cloud Messaging in an Ionic + Angular app is a straightforward process. By following these steps, you can enable push notifications and engage your users with timely updates and messages. Firebase provides a robust platform for managing and sending notifications, enhancing the user experience of your app. Happy coding!

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