How to Send Push Notifications to the iOS Simulator

As of Xcode 11.4 beta, you can!

Push notifications are one of the most popular ways for developers to keep users engaged in their apps. In iOS applications, push notifications can be incorporated by using the Apple Push Notification service (APNs).

However, it’s not as easy as it sounds since there is a long list of things to do for setting this up. Plus, what’s worse is that we have to use a real device to test if push notifications are working or not since push notifications aren’t supported in Xcode’s iOS Simulator.

But I have some good news for you. Xcode 11.4 beta is out and the best part about this release for me is that we can finally test push notifications in the iOS Simulator!

The release note of Xcode 11.4 beta consists of a section that says:

“Simulator supports simulating remote push notifications, including background content fetch notifications. In Simulator, drag and drop an APNs file onto the target simulator. The file must be a JSON file with a valid Apple Push Notification Service payload, including the “aps” key. It must also contain a top-level “Simulator Target Bundle” with a string value matching the target application‘s bundle identifier.

simctl also supports sending simulated push notifications. If the file contains “Simulator Target Bundle” the bundle identifier is not required, otherwise you must provide it as an argument (8164566):

$ xcrun simctl push <device> com.example.my-app ExamplePush.apns"

We’ll go in-depth about what this means in the latter part of the post. But for now, let’s be happy because the hassle of having to use a real device for testing push notifications is finally gone.

How Do We Do It?

So, now, let’s see how we can use this newly-arrived feature of Xcode 11.4 beta. For this, you obviously need to have Xcode 11.4 beta or higher. I currently have Xcode 11.4 beta.

Now, let’s create a new project. I’ve named it TestPushNotifications and the user interface I chose is Storyboard. You can choose SwiftUI if you want.

Just to make the app look good (though it won’t help…), I’ve added a UILabel that says “Hello, world!” in View Controller of Main.storyboard.

Now, when we run the app in a simulator, iPhone 11 Pro Max in this case, it looks like this:

This is where the fun begins! Let’s go to the AppDelegate.swift file and add the following line below import UIKit to import Apple’s UserNotifications framework.

import UserNotifications

Now, in the AppDelegate class, let’s create a function, registerForPushNotifications(), that requests permission from the user to allow the app to send push notifications.

Let’s call the function we just created, from the application(_:didFinishLaunchingWithOptions:) method of AppDelegate.

For that, add registerForPushNotifications() above the return true statement. Your AppDelegate.swift file will look something like this:

//
//  AppDelegate.swift
//  TestPushNotifications
//


import UIKit
import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

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

    // MARK: UISceneSession Lifecycle

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
        // Called when the user discards a scene session.
        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
    }
    
    func registerForPushNotifications() {
        UNUserNotificationCenter.current()
            .requestAuthorization(options: [.alert, .sound, .badge]) {
                (granted, error) in
                print("Permission granted: \(granted)")
        }
    }
    
}

When we run the app, we get a dialog asking for permission to allow the app to send push notifications. Tap Allow.

Dialog asking for permission from the user to allow the app to send push notifications

The release note of Xcode 11.4 beta says:

"simctl also supports sending simulated push notifications. If the file contains “Simulator Target Bundle”, the bundle identifier is not required, otherwise, you must provide it as an argument (8164566):

$ xcrun simctl push <device> com.example.my-app ExamplePush.apns"

Now, let’s try what it says. For that, we require a JSON file with a valid Apple Push Notification Service payload.

Apple’s documentation, entitled “Generating a Remote Notification”, gives a clear idea about how we can create such a file. I’m creating a file named notification.apns on my desktop and adding the following content in it:

{
    "aps": {
        "alert": "Push Notifications Test",
        "sound": "default",
        "badge": 1
    }
}


After the file has been created, we can open the terminal and use the command given in the release note:
$ xcrun simctl push <device> com.example.my-app ExamplePush.apns

Here, <device> is to be replaced by the device identifier, com.example.my-app is to be replaced by your project’s bundle identifier, and ExamplePush.apns is to be replaced by the filename of our apns file.

Note that the bundle identifier is not necessary in the command, if you add it with the “Simulator Target Bundle” key in the apns file.

You can retrieve your simulator’s device identifier by following the steps shown in the GIF below:










Finding the device identifier of the simulator we are using (iPhone 11 Pro Max, in this case)

And you can retrieve the bundle identifier of your project by following the steps shown in the GIF below:










Finding the bundle identifier of the project

Before we execute the command, we have to send the app to the background first. That’s how the push notification will be visible.


Note: If you want the push notification to be visible even when the app is on the foreground, you can make AppDelegate conform to UNUserNotificationCenterDelegate and implement its userNotificationCenter(_:willPresent:withCompletionHandler:) method. And make sure that you have included the following line before calling registerForPushNotifications() in application(_:didFinishLaunchingWithOptions:) method:

UNUserNotificationCenter.current().delegate = self




Now, let’s execute the command. In my case, the command is:
$ xcrun simctl push 25A9FF1A-000B-4F36-B44C-43AC7BCD0958 np.com.sagunrajlage.TestPushNotifications notification.apns

As soon as it is executed, this is what we can see in the simulator — a push notification:










A push notification in Simulator

That’s how we can run a command to show push notifications in our simulator!

But wait, if you are not quite comfortable with using the terminal, there’s another way. Remember what the release note said?


“In Simulator, drag and drop an APNs file onto the target simulator. The file must be a JSON file with a valid Apple Push Notification Service payload, including the “aps” key. It must also contain a top-level “Simulator Target Bundle” with a string value matching the target application‘s bundle identifier.”


We can simply drag and drop our apns file into the simulator to get a push notification. But for that, we will have to make some modifications in the apns file.

In the notification.apns file that we created previously, let’s add one more key, "Simulator Target Bundle”, which will hold the value of our bundle identifier, which is “np.com.sagunrajlage.TestPushNotifications” in my case.

So, the file will look like this:

{
    "Simulator Target Bundle": "np.com.sagunrajlage.TestPushNotifications",
    "aps": {
        "alert": "Push Notifications Test",
        "sound": "default",
        "badge": 1
    }
}


Now, drag and drop this file over to the simulator and see the magic!











And that’s another way to test push notifications in the iOS Simulator.

This is a great addition to the upcoming versions of Xcode because it saves us from a lot of hassle. Keep it up, Apple!

Happy coding!