Leveraging Broadcast Push Notifications for Live Activities in iOS 18

 

Apple has introduced an innovative way to broadcast updates to a large audience with a single push notification in iOS 18. This new capability, known as Broadcast Push Notifications, allows apps to send updates to multiple devices at once, ensuring Live Activities remain up-to-date efficiently. In this blog, we will explore how to use this feature with ActivityKit and Apple Push Notification Service (APNs), complete with code examples.

What Are Live Activities?

Live Activities allow users to track ongoing events directly from the Lock Screen or Dynamic Island. They are commonly used for tracking deliveries, live sports scores, or flight updates. Traditionally, updating a Live Activity required sending unique push notifications for each device, which could be inefficient when reaching a large audience.

Introducing Broadcast Push Notifications

With iOS 18, developers can now use Broadcast Push Notifications to send a single update to all users subscribed to a particular channel. A channel is a unique identifier for a shared event, such as a sports game or flight status.

How It Works:

  1. Create a Channel — A unique channel ID is generated.
  2. Subscribe to the Channel — Live Activities listen for updates via the channel.
  3. Send Broadcast Push Notification — A single notification updates all subscribers.

Step-by-Step Implementation

1. Enabling Broadcast Push Notifications

Before integrating broadcast updates, enable the capability in the Apple Developer Portal:

  1. Navigate to Certificates, Identifiers & Profiles.
  2. Select your app ID and enable Broadcast Push Notifications under Push Notifications.

2. Creating a Channel

You can create a channel using Push Notifications Console or via API.

Creating a Channel via Push Notifications Console:

  1. Open the Push Notifications Console.
  2. Navigate to Channels and select New Channel.
  3. Choose an environment (Development or Production).
  4. Select a Message Storage Policy:
  • No Storage: Updates are only delivered to online devices.
  • Most Recent Message: Stores the latest update for new subscribers.

5. Click Create Channel to generate a channel ID.

3. Subscribing to a Channel in Your App

Once a channel is created, your app must subscribe to it before starting a Live Activity.

Requesting a Channel ID from the Server

func fetchChannelID(for event: String, completion: @escaping (String?) -> Void) {
    let url = URL(string: "https://yourserver.com/getChannelID?event=\(event)")!
    URLSession.shared.dataTask(with: url) { data, response, error in
        guard let data = data, let channelID = String(data: data, encoding: .utf8) else {
            completion(nil)
            return
        }
        completion(channelID)
    }.resume()
}

Starting a Live Activity with a Channel ID

import ActivityKit

struct SportsActivityAttributes: ActivityAttributes {
    public struct ContentState: Codable, Hashable {
        var homeTeamScore: Int
        var awayTeamScore: Int
    }
    var eventName: String
}
func startLiveActivity(channelID: String) {
    let attributes = SportsActivityAttributes(eventName: "Soccer Match")
    let initialState = SportsActivityAttributes.ContentState(homeTeamScore: 0, awayTeamScore: 0)
    
    let activityContent = ActivityContent(state: initialState, staleDate: nil)
    
    do {
        let activity = try Activity<SportsActivityAttributes>.request(attributes: attributes, content: activityContent, pushType: .channel(channelID))
        print("Live Activity started with channel ID: \(channelID)")
    } catch {
        print("Error starting Live Activity: \(error)")
    }
}

4. Sending a Broadcast Push Notification

Broadcast push notifications must be sent through APNs using your backend server.

APNs Payload Example:

{
    "aps": {
        "timestamp": 1710500000,
        "alert": "Home Team leads 2-1!",
        "mutable-content": 1
    },
    "channel": "base64_encoded_channel_id"
}

Sending Notification via cURL:

curl -v -d '{
  "aps": {"alert": "Goal! Home Team scores!", "mutable-content": 1},
  "channel": "your_channel_id"
}' \
-H "apns-topic: com.yourapp.push-type.liveactivity" \
-H "authorization: bearer YOUR_AUTH_TOKEN" \
--http2 https://api.push.apple.com/3/device/YOUR_DEVICE_TOKEN

5. Managing Channels

The total number of channels is limited, so removing inactive ones is recommended.

Deleting a Channel via API:

curl -X DELETE "https://api.push.apple.com/3/channel/YOUR_CHANNEL_ID" \
-H "authorization: bearer YOUR_AUTH_TOKEN"

Conclusion

Broadcast Push Notifications significantly improve efficiency when updating Live Activities for large audiences. By leveraging APNs channels, developers can now:

  • Reduce the overhead of storing individual push tokens.
  • Send a single notification to multiple devices.
  • Improve the user experience by ensuring timely updates.

Start experimenting with Broadcast Push Notifications today and enhance your app’s Live Activity experience!

🔗 Additional Resources:

🚀 Happy coding!

Comments

Post a Comment

Popular posts from this blog

Dependency Injection in iOS with SwiftUI

Image
  A Beginner-Friendly Guide to Building Modular, Testable Apps Dependency Injection (DI) is a powerful design pattern that helps you write  more modular, testable, and maintainable code . In SwiftUI, while the framework encourages composition and simplicity, adopting DI can elevate your architecture — especially as your app grows. In this post, you’ll learn: What Dependency Injection is Why it’s useful in SwiftUI apps Different DI techniques in Swift Real-world SwiftUI examples with DI Best practices and when to use DI 🧠 What is Dependency Injection? Dependency Injection  means providing an object with its dependencies from the outside instead of creating them internally. Think of it this way: instead of a class  making  its own tools, it is  handed  the tools it needs. Without DI: class UserViewModel { private var userService = UserService () } With DI: class UserViewModel { private var userService: UserService init ( userService : U...
Read more

Using Core ML with SwiftUI: Build an AI-Powered App

Image
  Artificial Intelligence (AI) is revolutionizing mobile app experiences, and with  Core ML , Apple makes it easy to integrate machine learning into iOS applications. When combined with  SwiftUI , you can create powerful, AI-driven applications with a modern and interactive UI. In this guide, we’ll explore how to integrate  Core ML  into a SwiftUI app, process images, and display real-time AI-powered results. What is Core ML? Core ML is Apple’s machine learning framework that allows developers to integrate trained models into iOS apps for tasks like  image recognition, text analysis, and object detection . Key Benefits of Core ML: ✅ Optimized for Apple hardware (fast and efficient on-device processing) ✅ Supports popular ML models like Vision, Natural Language Processing (NLP), and Sound Analysis ✅ Works  offline  without needing an internet connection ✅ Ensures privacy by running models on-device Step 1: Get a Pre-Trained Core ML Model You can do...
Read more

CI/CD for iOS Projects with Xcode: A Complete Guide

Image
  Continuous Integration and Continuous Deployment (CI/CD) are essential for iOS developers looking to streamline their development workflow, improve code quality, and automate testing and deployment. In this guide, we’ll walk through setting up CI/CD for an iOS project using Xcode, GitHub Actions, and Fastlane. Why CI/CD for iOS Development? CI/CD automates the process of testing, building, and deploying iOS applications, ensuring: Faster feedback loops Reduced manual errors Higher code quality Efficient team collaboration Prerequisites Before setting up CI/CD, ensure you have: A macOS machine with Xcode installed A GitHub repository for your iOS project An Apple Developer Account Fastlane installed ( brew install fastlane ) A valid development certificate and provisioning profile Step 1: Setting Up GitHub Actions for CI 1.1 Creating a GitHub Actions Workflow GitHub Actions automates building and testing iOS apps. To set it up: Inside your project, navigate to  .github/workfl...
Read more