Swift API & SDK Docs 9.0.1

In this guide, we'll create a simple "Hello, World" application that demonstrates the core concepts of PubNub

PubNub

PubNub is a real-time messaging platform that provides APIs and SDKs for building scalable applications. It handles the complex infrastructure of real-time communication, including:

:

  • Setting up a connection
  • Sending messages
  • Receiving messages in real-time

Overview​

This guide will help you get up and running with PubNub in your Swift application. Since Swift is commonly used across different platforms, we provide two implementation paths:

  • SwiftUI: For developers building iOS apps using SwiftUI
  • UIKit: For developers building iOS apps using UIKit

The core PubNub concepts and API usage remain the same across both paths, but implementation details like lifecycle management and UI updates differ. Select the appropriate tab in each section to see platform-specific guidance.

While this guide focuses on Swift for Apple platforms, the PubNub Swift SDK is also compatible with Linux environments.

Prerequisites​

Before we dive in, make sure you have:

  • A basic understanding of Swift
  • Xcode 14.0 or later
  • A PubNub account (we'll help you set this up!)

Setup​

Get your PubNub keys​

First things first – you'll need your PubNub keys to get started. Here's how to get them:

  • Sign in or create an account on the PubNub Admin Portal.
  • Create a new app (or use an existing one).
  • Find your publish

    Publish Key

    A unique identifier that allows your application to send messages to PubNub channels. It's part of your app's credentials and should be kept secure.
     and subscribe

    Subscribe Key

    A unique identifier that allows your application to receive messages from PubNub channels. It's part of your app's credentials and should be kept secure.
     keys in the app's dashboard.

When you create a new app, PubNub automatically generates your first set of keys. While you can use the same keys for development and production, we recommend creating separate keysets for each environment for better security and management.

Install the SDK​

SDK version

Always use the latest SDK version to have access to the newest features and avoid security vulnerabilities, bugs, and performance issues.

Choose one of these methods to add the Swift SDK to your iOS app:

Swift Package Manager​

  1. In Xcode, select File > Add Package Dependency....
  2. Enter the package URL: https://github.com/pubnub/swift.git.
  3. Select Up to Next Major Version with "9.0.1" as the minimum version.
  4. From the list of package products, assign PubNubSDK to your target application.
  5. Click Add Package.

CocoaPods​

  1. Install CocoaPods if you haven't already: gem install cocoapods

  2. Add PubNub to your Podfile:

    pod 'PubNubSwift', '~> 9.0.1'

  3. Run pod install in your project directory

  4. Open the generated .xcworkspace file

Carthage​

  1. Add PubNub to your Cartfile:

    github "pubnub/swift" ~> 9.0.1

  2. Run carthage update --use-xcframeworks.

  3. Drag the built PubNub.xcframework into your Xcode project's Frameworks, Libraries, and Embedded Content section.

You can integrate the PubNub Swift SDK into any Swift application:

Swift Package Manager​

Add PubNub as a dependency to your Package.swift file:

dependencies: [
  .package(url: "https://github.com/pubnub/swift.git", from: "9.0.1")
]

Manual integration​

  1. Clone the repository:

    git clone https://github.com/pubnub/swift.git

  2. Include the Swift package in your project as a dependency.

Steps​

Initialize PubNub​

In your Swift application, you'll need to initialize the PubNub client with your unique keys to establish a connection to the PubNub network. This is the minimum configuration required to send and receive messages with PubNub in your application.

Make sure to replace the demo keys with your app's publish and subscribe keys from the Admin Portal.

  1. Create a view model class and keep a strong reference to your PubNub instance:

    import SwiftUI
    import PubNubSDK

    class PubNubViewModel: ObservableObject {
      // Reference to the SDK instance
      private let pubnub: PubNub

      init() {
        // PubNub instance configured with publish/subscribe keys and unique user ID
        pubnub = PubNub(configuration: PubNubConfiguration(
          publishKey: "demo",
          subscribeKey: "demo",
          userId: "device-\(UUID().uuidString.prefix(8))"
        ))    
      }
    show all 16 lines

  2. Initialize the view model in your App entry point:

    import SwiftUI
    import PubNubSDK

    @main
    struct MyApp: App {
      var body: some Scene {
        WindowGroup {
          ContentView()
            .environmentObject(PubNubViewModel())
        }
      }
    }

  3. Access the view model in your view using @EnvironmentObject:

    import SwiftUI
    import PubNubSDK

    struct ContentView: View {
      @EnvironmentObject var pubNubViewModel: PubNubViewModel
      
      var body: some View {
        Text("Hello, PubNub!")
      }
    }

For more information, refer to the Configuration section of the SDK documentation.

Set up event listeners​

Listeners help your app react to events and messages. You can implement custom app logic to respond to each type of message or event received. This is essential for building interactive real-time applications with PubNub.

  1. Add a @Published property to PubNubViewModel to store incoming messages:

    @Published var messages: [String] = []

  2. In the same class, create a Subscription object for your channel and set up event listeners in the setupMessageHandling() method to handle PubNub events:

    import SwiftUI
    import PubNubSDK

    class PubNubViewModel: ObservableObject {
      // Holds the streamed messages
      @Published var messages: [String] = []
      // Reference to the SDK instance
      private let pubnub: PubNub

      // A dedicated subscription object for the example chat channel
      lazy var subscription: Subscription? = pubnub
        .channel("hello_world")
        .subscription(options: ReceivePresenceEvents())

      init() {
    show all 49 lines

For more information, refer to the Listeners section of the SDK documentation.

Trigger a subscription​

To receive messages sent to a particular channel, you subscribe to it. When you subscribe to a channel, you'll receive all messages published to that channel in real-time.

It is best to define the subscription before you introduce the listeners and then send the subscribe() call, so place the relevant code in the appropriate places within your app.

The following example demonstrates how to subscribe to a channel when a view appears and unsubscribe when it disappears:

import SwiftUI
import PubNubSDK

struct ContentView: View {
  @EnvironmentObject var pubNubViewModel: PubNubViewModel
  
  var body: some View {
    List(pubNubViewModel.messages, id: \.self) { message in
      Text(message)
    }
    .onAppear {
      pubNubViewModel.subscription?.subscribe()
    }
    .onDisappear {
      pubNubViewModel.subscription?.unsubscribe()
show all 18 lines

Publish messages​

When you publish a message to a channel, PubNub delivers that message to everyone who subscribes to that channel. In this app, publishing a message is triggered when the status listener detects a successful connection to a channel.

A message can be any type of JSON-serializable data (such as objects, arrays, integers, strings) that is smaller than 32 KiB.

Implement the sendWelcomeMessage() method defined earlier:

// Called when the connection is established
func sendWelcomeMessage() {
  pubnub.publish(
    channel: "hello_world",
    message: "Hello from iOS!"
  ) { result in
    switch result {
    case .success(let response):
      print("Message published successfully at \(response.timetokenDate)")
    case .failure(let error):
       print("Failed to publish message: \(error.localizedDescription)")
    }
  }
}

Run the app​

Once you've implemented the initialization, event listeners, subscription, and publishing functionality, you're ready to run your application and test the real-time messaging capabilities.

Follow these steps:

  1. Build and run your app in Xcode (⌘+R).
  2. Wait for the connection to establish (check the console for status updates).
  3. You should see the welcome message appear when the connection is successful.
  4. Try sending messages using the UI you've created.

When you run the application, you should see output similar to the following:

Connection status changed: connected
Message published successfully at 2023-10-23 15:42:36 +0000
Message received: Hello from iOS!

Complete example​

Download the complete working example that puts everything together.

Troubleshooting​

If you don't see the expected output, here are some common issues and how to fix them:

IssuePossible Solutions
No connection message
  • Check your internet connection.
  • Verify your publish and subscribe keys are correct.
  • Make sure you're not behind a firewall blocking PubNub's connections.
Message not received
  • Double-check that you're subscribed to the correct channel.
  • Verify that the message was actually sent (check for any error messages).
  • Make sure you're waiting long enough for the message to be delivered.
Build errors
  • Ensure you've added the PubNub dependency correctly.
  • Check that you're using a compatible version of Swift.
  • Make sure all imports are correct.

Next steps​

Great job! 🎉 You've successfully created your first PubNub application. Here are some exciting things you can explore next:

  • Learn about the Swift Chat SDK for ready-to-use chat features.
  • Implement user presence to show who's online.
  • Add typing indicators and read receipts.
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