Detect network changes on macOS

NetworkChangeDetector-main.swift

//
//  main.swift
//  NetworkChangeDetector
//
//  Created by Hao Guan on 2021/8/30.
//

import Foundation
import Network
import CoreWLAN

// 对于执行 shell 命令进行简单的封装
@discardableResult
func shell(prog: String, args: [String]) -> Bool {
    let task = Process()
    task.launchPath = prog
    task.arguments = args
    task.launch()
    return task.isRunning
}

// 创建网络状态变化检测
let monitor = NWPathMonitor()
monitor.pathUpdateHandler = { path in
    // 无网络  
    if path.status == .unsatisfied {
        print("No network.")
        return
    }
    
    // 已联网的接口
    print("Online interfaces: \(path.availableInterfaces)")
    
    var first = true
    for iface in path.availableInterfaces {
        let msg: String
        // 以太网，获取网关
        if iface.type == .wiredEthernet {
            msg = "\(iface.name): Ethernet with \(path.gateways)."
        // Wi-Fi，获取 SSID
        } else if iface.type == .wifi {
            let client = CWWiFiClient().interface(withName: iface.name)
            let ssid = client?.ssid() ?? "<No SSID>"
            msg = "\(iface.name): Wi-Fi called \(ssid)"
        } else {
            msg = "\(iface.name) other type."
        }

        // 默认接口
        if first {
            print("* \(msg)")
            first = false
        } else {
            print("  \(msg)")
        }
    }

    // 执行脚本
    // shell(prog: "/bin/ls", args: ["/"])
}

// 开始监听网络变化
let queue = DispatchQueue.global(qos: .background)
monitor.start(queue: queue)

// 阻塞主线程，让程序在后台持续运行
let group = DispatchGroup()
group.enter()
let _ = group.wait(timeout: .distantFuture)