从iOS 12开始，NWPathMonitor取代了Reachability。用这个:

import Network


struct Internet {
 
 private static let monitor = NWPathMonitor()
 
 static var active = false
 static var expensive = false
 
 /// Monitors internet connectivity changes. Updates with every change in connectivity.
 /// Updates variables for availability and if it's expensive (cellular).
 static func start() {
  guard monitor.pathUpdateHandler == nil else { return }
  
  monitor.pathUpdateHandler = { update in
   Internet.active = update.status == .satisfied ? true : false
   Internet.expensive = update.isExpensive ? true : false
  }
  
  monitor.start(queue: DispatchQueue(label: "InternetMonitor"))
 }
 
}

在使用:

Internet.start()

if Internet.active {
 // do something
}
  
if Internet.expensive {
 // device is using Cellular data or WiFi hotspot
}

这里是我的解决方案swift 2.3与库(reach .swift)

进入你的Podfile并添加:

pod 'ReachabilitySwift', '~> 2.4' // swift 2.3

然后进入您的终端:

pod install

然后创建一个新的文件ReachabilityManager并添加下面的代码:

import Foundation
import ReachabilitySwift

enum ReachabilityManagerType {
    case Wifi
    case Cellular
    case None
}

class ReachabilityManager {
    static let sharedInstance = ReachabilityManager()

    private var reachability: Reachability!
    private var reachabilityManagerType: ReachabilityManagerType = .None


    private init() {
        do {
            self.reachability = try Reachability.reachabilityForInternetConnection()
        } catch {
            print("Unable to create Reachability")
            return
        }

        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ReachabilityManager.reachabilityChanged(_:)),name: ReachabilityChangedNotification,object: self.reachability)
        do{
            try self.reachability.startNotifier()
        }catch{
            print("could not start reachability notifier")
        }
    }

    @objc private func reachabilityChanged(note: NSNotification) {

        let reachability = note.object as! Reachability

        if reachability.isReachable() {
            if reachability.isReachableViaWiFi() {
                self.reachabilityManagerType = .Wifi
            } else {
                self.reachabilityManagerType = .Cellular
            }
        } else {
            self.reachabilityManagerType = .None
        }
    }
}

extension ReachabilityManager {

    func isConnectedToNetwork() -> Bool {
        return reachabilityManagerType != .None
    }

}

如何使用:

进入你的AppDelegate.swift并添加下面的代码:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
     ReachabilityManager.sharedInstance
}

然后，当你想检查设备是否连接到互联网时，请:

if ReachabilityManager.sharedInstance.isConnectedToNetwork() {
   // Connected
} else {
  // Not connected
}

如果你的项目有一个高于或等于iOS 12的目标，并使用组合，你可以使用这一小段代码。

import Combine
import Network

enum NerworkType {
    case wifi
    case cellular
    case loopBack
    case wired
    case other
}

protocol ReachabilityServiceContract {
    var reachabilityInfos: PassthroughSubject<NWPath, Never> { get set }
    var isNetworkAvailable: CurrentValueSubject<Bool, Never> { get set }
    var typeOfCurrentConnection: PassthroughSubject<NerworkType, Never> { get set }
}

final class ReachabilityService: ReachabilityServiceContract {
    var reachabilityInfos: PassthroughSubject<NWPath, Never> = .init()
    var isNetworkAvailable: CurrentValueSubject<Bool, Never> = .init(false)
    var typeOfCurrentConnection: PassthroughSubject<NerworkType, Never> = .init()

    private let monitor: NWPathMonitor
    private let backgroudQueue = DispatchQueue.global(qos: .background)

    init() {
        monitor = NWPathMonitor()
        setUp()
    }

    init(with interFaceType: NWInterface.InterfaceType) {
        monitor = NWPathMonitor(requiredInterfaceType: interFaceType)
        setUp()
    }

    deinit {
        monitor.cancel()
    }
}

private extension ReachabilityService {
    func setUp() {
    
        monitor.pathUpdateHandler = { [weak self] path in
            self?.reachabilityInfos.send(path)
            switch path.status {
            case .satisfied:
                self?.isNetworkAvailable.send(true)
            case .unsatisfied, .requiresConnection:
                self?.isNetworkAvailable.send(false)
            @unknown default:
                self?.isNetworkAvailable.send(false)
            }
            if path.usesInterfaceType(.wifi) {
                self?.typeOfCurrentConnection.send(.wifi)
            } else if path.usesInterfaceType(.cellular) {
                self?.typeOfCurrentConnection.send(.cellular)
            } else if path.usesInterfaceType(.loopback) {
                self?.typeOfCurrentConnection.send(.loopBack)
            } else if path.usesInterfaceType(.wiredEthernet) {
                self?.typeOfCurrentConnection.send(.wired)
            } else if path.usesInterfaceType(.other) {
                self?.typeOfCurrentConnection.send(.other)
            }
        }
    
        monitor.start(queue: backgroudQueue)
    }
}

只要订阅你想要跟踪的变量，你就会得到任何变化的更新。

虽然它可能不能直接确定手机是否连接到网络，但最简单的解决方案是“ping”谷歌或其他服务器(除非手机连接到网络，否则这是不可能的):

private var urlSession:URLSession = {
    var newConfiguration:URLSessionConfiguration = .default
    newConfiguration.waitsForConnectivity = false
    newConfiguration.allowsCellularAccess = true
    return URLSession(configuration: newConfiguration)
}()

public func canReachGoogle() -> Bool
{
    let url = URL(string: "https://8.8.8.8")
    let semaphore = DispatchSemaphore(value: 0)
    var success = false
    let task = urlSession.dataTask(with: url!)
    { data, response, error in
        if error != nil
        {
            success = false
        }
        else
        {
            success = true
        }
        semaphore.signal()
    }

    task.resume()
    semaphore.wait()

    return success
}

如果您担心服务器可能宕机或阻塞您的IP，您总是可以以类似的方式ping多个服务器，并返回它们中的任何一个是否可达。或者让别人专门为这个目的设置一个专用服务器。

对于Swift 3, Swift 4(使用蜂窝和Wi-Fi):

import SystemConfiguration

public class Reachability {

    class func isConnectedToNetwork() -> Bool {

        var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
            }
        }

        var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags(rawValue: 0)
        if SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) == false {
            return false
        }

        /* Only Working for WIFI
        let isReachable = flags == .reachable
        let needsConnection = flags == .connectionRequired

        return isReachable && !needsConnection
        */

        // Working for Cellular and WIFI
        let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        let ret = (isReachable && !needsConnection)

        return ret

    }
}

用法:

if Reachability.isConnectedToNetwork(){
    print("Internet Connection Available!")
}else{
    print("Internet Connection not Available!")
}

在项目中创建一个新的Swift文件，命名为Reachability.swift。将以下代码剪切并粘贴到其中以创建您的类。

import Foundation
import SystemConfiguration

open class Reachability {
    
    class func isConnectedToNetwork() -> Bool {
        
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)
        
        let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
            }
        }
        
        var flags = SCNetworkReachabilityFlags()
        if !SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) {
            return false
        }
        let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        return (isReachable && !needsConnection)
    }
}

你可以在代码的任何地方调用Reachability，就像

if Reachability.isConnectedToNetwork() {
    print("Network is connected")
} else {
    print("Network is not connected")
}