如何使用Swift找到免费的本地端口？

import Network

let endpoint = NWEndpoint.hostPort(host: NWEndpoint.Host.ipv4(.loopback), port: NWEndpoint.Port(integerLiteral: 0))

let parameters = NWParameters.tcp.copy()
parameters.requiredLocalEndpoint = endpoint

let listener = try NWListener(using: parameters)

listener.stateUpdateHandler = { state in
    switch state {
    case .ready:
        print("Listener started")
    case .failed(let error):
        print("Listener failed with error: \(error)")
    default:
        break
    }
}

listener.newConnectionHandler = { newConnection in
    // 处理新的连接
}

listener.start(queue: .main)