Connect to PhoenixFramework WebSocket from Swift.

ViewController.swift

import UIKit
import Starscream

class ViewController: UIViewController, WebSocketDelegate {
    var socket = WebSocket(url: URL(string: "ws://10.0.1.2:4000/socket/websocket")!, protocols: [])

    override func viewDidLoad() {
        super.viewDidLoad()
        socket.delegate = self
        socket.connect()
    }

    var ref: Int = 0

    // MARK: Websocket Delegate Methods.

    func websocketDidConnect(socket: WebSocket) {
        print("websocket is connected")

        ref += 1
        let dict = [
            "ref" : String(ref),
            "topic": "room:ebe99a2c-cccb-4409-8bdd-d1d3b7fa2eb0",
            "event": "phx_join",
            "payload": ["name": "chu"]
        ] as [String : Any]

        let jsonData = try! JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)
        socket.write(data: jsonData)
    }

    func websocketDidDisconnect(socket: WebSocket, error: NSError?) {
        if let e = error {
            print("websocket is disconnected: \(e.localizedDescription)")
        } else {
             print("websocket disconnected")
        }
    }

    func websocketDidReceiveMessage(socket: WebSocket, text: String) {
        print("Received text: \(text)")
    }

    func websocketDidReceiveData(socket: WebSocket, data: Data) {
        print("Received data: \(data.count)")
    }

    func sendText() {
        ref += 1
        let dict = [
            "ref" : String(ref),
            "topic": "room:ebe99a2c-cccb-4409-8bdd-d1d3b7fa2eb0",
            "event": "new_msg",
            "payload": ["body": "hello"]
        ] as [String : Any]

        let jsonData = try! JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)

        socket.write(data: jsonData)
    }
}