WebSockets in Swift: Building Real-Time Apps in an Hour

Why WebSockets Are a Superpower for Swift Developers

Imagine: you open a messenger, and messages arrive instantly. No endless page refreshes, no "pull to refresh". This is the magic of real-time, and in Swift it's implemented using WebSockets. If you've only been using HTTP requests so far, you're missing out on a whole world of possibilities: online chats, stock quotes, live notifications, multiplayer games.

In this article, we'll break down how to add WebSockets to your Swift app. No fluff — only code you can copy and run. By the end, you'll be able to write your first real-time chat in less than an hour. Let's go!

What Are WebSockets and How Are They Better Than REST API?

WebSockets is a protocol for two-way communication between client and server. Unlike REST, where the client constantly "pings" the server with questions, WebSocket establishes a persistent connection. The server can send data on its own whenever it appears. It's like the difference between constantly calling a friend "Are you there yet?" and simply opening the door to let them in.

For a Swift developer, the main advantage is saving traffic and resources. Instead of dozens of HTTP requests per minute — one single connection. Perfect for trading apps, online games, system monitoring.

When Should You Use WebSockets in iOS?

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• Online chats — messages must be delivered instantly.
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• Stock quotes — prices change every second.
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• Multiplayer games — synchronizing player actions.
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• Real-time notifications — new like, order, message.
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• IoT applications — sensor data arrives continuously.
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But don't use WebSockets everywhere. If you just need to load a product list — a regular HTTP GET will do better. WebSocket is justified when data updates more often than once every 10 seconds.

Setting Up WebSocket in Swift: From Zero to First Connection

Swift has built-in WebSocket support — the URLSessionWebSocketTask class. No third-party libraries needed. Let's write a simple client.

Step 1. Create a WebSocket Connection

import Foundation\n\nclass WebSocketManager: NSObject {\n    private var webSocketTask: URLSessionWebSocketTask?\n    private let session: URLSession\n    \n    override init() {\n        self.session = URLSession(configuration: .default, delegate: nil, delegateQueue: OperationQueue())\n        super.init()\n    }\n    \n    func connect(to url: URL) {\n        webSocketTask = session.webSocketTask(with: url)\n        webSocketTask?.resume()\n        print("WebSocket connection established")\n        receiveMessage()\n    }\n    \n    func disconnect() {\n        webSocketTask?.cancel(with: .normalClosure, reason: nil)\n        print("Connection closed")\n    }\n}\n

This is a basic wrapper. The resume() method starts the connection — without it, nothing will happen. Remember this as a mantra: always call resume().

Step 2. Send and Receive Messages

extension WebSocketManager {\n    func sendMessage(_ text: String) {\n        let message = URLSessionWebSocketTask.Message.string(text)\n        webSocketTask?.send(message) { error in\n            if let error = error {\n                print("Send error: \\(error.localizedDescription)")\n            }\n        }\n    }\n    \n    private func receiveMessage() {\n        webSocketTask?.receive { [weak self] result in\n            switch result {\n            case .success(let message):\n                switch message {\n                case .string(let text):\n                    print("Received message: \\(text)")\n