Websocket in iOS – Swift basics

We can have a quick basic understanding of Websocket in iOS. A WebSocket connection is a bi-directional, full-duplex communication protocol over a single, long-lived TCP connection. Unlike traditional HTTP, where a client must initiate every request and wait for a response, WebSockets allow both the client and server to send messages to each other at any time.

What is a WebSocket in iOS?

• Protocol: ws:// or wss:// (secure)
• Persistent: Keeps the connection open between client and server.
• Real-time: Ideal for apps needing real-time data (e.g., chat, games, stock prices).
• Low-latency: No need to re-establish connection on each request (unlike HTTP).

Where it is used in mobile application ?

In mobile apps (iOS/Android), WebSocket is typically used for:

• Chat apps – Real-time messaging.
• Live notifications – Push updates from server.
• Online multiplayer games – Real-time game state sync.
• Live tracking apps – GPS location updates.
• Stock/crypto price monitoring – Instant data updates.

WebSocket vs HTTP APIs (REST)

How to use WebSocket in iOS (Swift) — Basic Example

import Foundation

class WebSocketManager: NSObject {
    var webSocketTask: URLSessionWebSocketTask?

    func connect() {
        let url = URL(string: "wss://example.com/socket")!
        webSocketTask = URLSession(configuration: .default).webSocketTask(with: url)
        webSocketTask?.resume()
        receiveMessage()
    }

    func send(message: String) {
        let msg = URLSessionWebSocketTask.Message.string(message)
        webSocketTask?.send(msg) { error in
            if let error = error {
                print("WebSocket sending error: (error)")
            }
        }
    }

    func receiveMessage() {
        webSocketTask?.receive { [weak self] result in
            switch result {
            case .success(let message):
                switch message {
                case .string(let text):
                    print("Received: (text)")
                default:
                    break
                }
                self?.receiveMessage() // Keep listening
            case .failure(let error):
                print("WebSocket receiving error: (error)")
            }
        }
    }

    func disconnect() {
        webSocketTask?.cancel(with: .goingAway, reason: nil)
    }
}

import Foundation

class WebSocketManager: NSObject {
    var webSocketTask: URLSessionWebSocketTask?

    func connect() {
        let url = URL(string: "wss://example.com/socket")!
        webSocketTask = URLSession(configuration: .default).webSocketTask(with: url)
        webSocketTask?.resume()
        receiveMessage()
    }

    func send(message: String) {
        let msg = URLSessionWebSocketTask.Message.string(message)
        webSocketTask?.send(msg) { error in
            if let error = error {
                print("WebSocket sending error: (error)")
            }
        }
    }

    func receiveMessage() {
        webSocketTask?.receive { [weak self] result in
            switch result {
            case .success(let message):
                switch message {
                case .string(let text):
                    print("Received: (text)")
                default:
                    break
                }
                self?.receiveMessage() // Keep listening
            case .failure(let error):
                print("WebSocket receiving error: (error)")
            }
        }
    }

    func disconnect() {
        webSocketTask?.cancel(with: .goingAway, reason: nil)
    }
}

When to Use WebSocket in a Mobile App?

Use WebSocket when:

• You need real-time two-way communication.
• REST API polling is too inefficient.
• You want lower battery usage compared to frequent polling.

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