Apple Network Framework. Swift UDP hello world

client.py

import socket

UDP_IP = "192.168.1.5"
UDP_PORT = 5000
MESSAGE = b"Hello, World!"

print("UDP target IP:", UDP_IP)
print("UDP target port:", UDP_PORT)
print("message:", MESSAGE)

sock = socket.socket(socket.AF_INET, # Internet
                     socket.SOCK_DGRAM) # UDP
sock.sendto(MESSAGE, (UDP_IP, UDP_PORT))

server.py

import socket

class UDPServer:
    UDP_IP = "192.168.1.5"
    UDP_PORT = 5000

    def __init__(self, ip: str = UDP_IP, port: int = UDP_PORT):
        self.udpSocket = socket.socket(
            socket.AF_INET,     # Internet
            socket.SOCK_DGRAM)  # UDP
        self.udpSocket.bind((ip, port))


        print("Serving on", ip, port)

        self.counterPacket = 1

        while True:
            try:
                data, addr = self.udpSocket.recvfrom(1024)  # buffer size is 1024 bytes
                print("Received message:", data, "from", addr)

                self.process(data, addr)

            except KeyboardInterrupt:
                print("\tClosed by an Interrupt")
                break


    def process(self, data: bytes, from_addr):
        print("Processing data:", data)

        if data == b"getLast":
            print("sending Counter = {}".format(self.counterPacket))
            self.udpSocket.sendto(bytes(self.counterPacket), from_addr)

            print("Sent... to", from_addr[0])

        self.counterPacket += 1

UDPServer()

UDPClient.swift

//
//  UDPClient.swift
//  NetworkUDP
//
//  Created by menangen on 31.08.2018.
//
//

import Foundation
import Network

class UDPClient {
    var connection: NWConnection
    var queue: DispatchQueue
    
    init() {
        queue = DispatchQueue(label: "UDP Client Queue")

        let host = NWEndpoint.Host.ipv4(IPv4Address("192.168.1.5")!)
        let port = NWEndpoint.Port(rawValue: 5000)!

        connection = NWConnection(to: .hostPort(host: host, port: port), using: .udp)
        connection.stateUpdateHandler = { (newState) in
            switch (newState) {
            case .ready:
                print("Ready to send")
            case .failed(let e):
                print("Client failed with error \(e)")
            default:
                break
            }
        }
        connection.start(queue: queue)
    }
    
    func send(_ number: UInt16) {
        let message = number == 0 ? "getLast" : String(number)
        
        connection.send(content: message.data(using: .ascii), completion: .contentProcessed({
                (error) in
                if let error = error {
                    print("Send error: \(error)")
                }
            })
        )
        
        connection.receive(minimumIncompleteLength: 4, maximumLength: 1024, completion: {
            (data, context, isComplete, error) in
            if data != nil {
                print("Received!", data ?? "Empty content")
            }
        })
        print("Sent...")
    }
}

ViewController.swift

//
//  ViewController.swift
//  NetworkUDP
//
//  Created by menangen on 29.08.2018.
//

import UIKit

class ViewController: UIViewController {
    let client: UDPClient
    
    required init?(coder aDecoder: NSCoder) {
        print("init coder style")
        self.client = UDPClient()
        super.init(coder: aDecoder)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.black
    }

    @IBAction func pressed() {
        print("Sending")
        self.client.send(0)
    }
}