Using Network.Framework sample for iOS12

network.swift

// Using Network.Framework sample for iOS12.
//   a server must run the command:
//   $ nc -l 3000

import UIKit
import Network

let connection = NWConnection(
	host: NWEndpoint.Host("localhost"),
	port: NWEndpoint.Port(rawValue: 3000)!,
	using: NWParameters(tls: nil))
let connected = DispatchSemaphore(value: 0)
connection.stateUpdateHandler = { state in
	if (state == .ready) {
		connected.signal()
	}
}
connection.start(queue: DispatchQueue.init(label: "sample"))
connected.wait()
let sent = DispatchSemaphore(value: 0)
connection.send(
	content: "Hello, World!\n".data(using: .utf8),
	completion: .contentProcessed(
		{ error in
			sent.signal()
		}))
sent.wait()
connection.cancel()