iOS12 Swift 4和Swift 5

如果你只是想检查连接，你的最低目标是iOS12，那么你可以使用NWPathMonitor

import Network

它需要一些属性的设置。

let internetMonitor = NWPathMonitor()
let internetQueue = DispatchQueue(label: "InternetMonitor")
private var hasConnectionPath = false

我创建了一个函数来启动它。你可以在viewdidload或其他地方做这个。我派了个保镖，你想怎么打就怎么打。

func startInternetTracking() {
    // only fires once
    guard internetMonitor.pathUpdateHandler == nil else {
        return
    }
    internetMonitor.pathUpdateHandler = { update in
        if update.status == .satisfied {
            print("Internet connection on.")
            self.hasConnectionPath = true
        } else {
            print("no internet connection.")
            self.hasConnectionPath = false
        }
    }
    internetMonitor.start(queue: internetQueue)
}

/// will tell you if the device has an Internet connection
/// - Returns: true if there is some kind of connection
func hasInternet() -> Bool {
    return hasConnectionPath
}

现在只需调用helper函数hasInternet()来查看是否有。它实时更新。请参阅Apple文档中的NWPathMonitor。它有更多的功能，如取消()，如果你需要停止跟踪连接，你正在寻找的互联网类型等。 https://developer.apple.com/documentation/network/nwpathmonitor

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

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(sizeofValue(zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(&zeroAddress) {
            SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, UnsafePointer($0))
        }

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

        let isReachable = flags == .Reachable
        let needsConnection = flags == .ConnectionRequired

        return isReachable && !needsConnection

    }
}

你可以使用下面的代码检查项目中的任何地方的互联网连接:

if Reachability.isConnectedToNetwork() {
    println("Internet connection OK")
} else {
    println("Internet connection FAILED")
}

如果用户没有连接到互联网，您可能希望向他们显示一个警告对话框来通知他们。

if Reachability.isConnectedToNetwork() {
    println("Internet connection OK")
} else {
    println("Internet connection FAILED")
    var alert = UIAlertView(title: "No Internet Connection", message: "Make sure your device is connected to the internet.", delegate: nil, cancelButtonTitle: "OK")
    alert.show()
}

解释:

我们正在制作一个可重用的公共类和方法，可以在项目的任何地方使用，以检查互联网连接。我们需要添加基础和系统配置框架。

在公共类Reachability中，方法isConnectedToNetwork() -> Bool{}将返回一个关于互联网连接的Bool值。我们使用if循环对case执行所需的操作。我希望这足够了。干杯!

There is no real way to do this, even APIs that do this will try to connect to a particular service and tell you if it succeed after previously failing, the best approach is to just try to connect to your service and handle the error appropriately, if you want some service that will notify you when you become connected, all that will happens is that it periodically calls to a fixed service until it gets a response and then let you know that it succeed, what if the problem is not the internet itself but the specific service you are trying to connect to.

最好的方法是在你的连接方法中设计处理这个问题的方法，你可以在给定的时间内触发重试，这取决于你的错误，也许是失败的数量，你可以返回一个错误，你可以用它来显示一个错误消息，给用户一个重试的可能性，也许是尝试几次，然后返回和错误的组合。

另一个类似的问题是发送你已经发送但还没有得到响应的消息，最好还是写你的应用程序来处理这个，忽略请求，直到它等待的请求返回，如果请求不同，取消等待请求，等等

这些东西可以以非常通用的方式编写，所以它们可以用于应用程序的许多不同方面，甚至不同的项目。

这是我的版本。本质上，它没有带来任何新东西。我把它绑定到UIDevice。

import UIKit
import SystemConfiguration

extension UIDevice {

    open class var isConnectedToNetwork: Bool {
        get {
            var zeroAddress = sockaddr_in()
            zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
            zeroAddress.sin_family = sa_family_t(AF_INET)

            guard
                let defaultRouteReachability: SCNetworkReachability = withUnsafePointer(to: &zeroAddress, {
                    $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                        SCNetworkReachabilityCreateWithAddress(nil, $0)
                    }
                }),
                var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags() as SCNetworkReachabilityFlags?,
                SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags)
                else { return false }

            return flags.contains(.reachable) && !flags.contains(.connectionRequired)
        }
    }

}

print("Network status availability: " + ( UIDevice.isConnectedToNetwork ? "true" : "false" ))

我已经检查了实现阿什利米尔的可达性类没有可可荚/依赖管理器。其思想是使项目中的可达性依赖项免费。

Xcode 7.2 - Swift 2.1

1) https://github.com/ashleymills/Reachability.swift。下载将Reachability类添加到项目中。

注:添加时，请确保勾选“如需复制项目”。

2)创建一个AppManager.swift类。这个类将迎合公共模型类，其中公共方法和数据将被添加，可以在任何VC中使用。

//  AppManager.swift

import UIKit
import Foundation

class AppManager: NSObject{
    var delegate:AppManagerDelegate? = nil
    private var _useClosures:Bool = false
    private var reachability: Reachability?
    private var _isReachability:Bool = false
    private var _reachabiltyNetworkType :String?

    var isReachability:Bool {
        get {return _isReachability}
    }  
   var reachabiltyNetworkType:String {
    get {return _reachabiltyNetworkType! }
   }   




    // Create a shared instance of AppManager
    final  class var sharedInstance : AppManager {
        struct Static {
            static var instance : AppManager?
        }
        if !(Static.instance != nil) {
            Static.instance = AppManager()

        }
        return Static.instance!
    }

    // Reachability Methods
    func initRechabilityMonitor() {
        print("initialize rechability...")
        do {
            let reachability = try Reachability.reachabilityForInternetConnection()
            self.reachability = reachability
        } catch ReachabilityError.FailedToCreateWithAddress(let address) {
            print("Unable to create\nReachability with address:\n\(address)")
            return
        } catch {}
        if (_useClosures) {
            reachability?.whenReachable = { reachability in
                self.notifyReachability(reachability)
            }
            reachability?.whenUnreachable = { reachability in
                self.notifyReachability(reachability)
            }
        } else {
            self.notifyReachability(reachability!)
        }

        do {
            try reachability?.startNotifier()
        } catch {
            print("unable to start notifier")
            return
        }


    }        
    private func notifyReachability(reachability:Reachability) {
        if reachability.isReachable() {
            self._isReachability = true

//Determine Network Type 
      if reachability.isReachableViaWiFi() {   
        self._reachabiltyNetworkType = CONNECTION_NETWORK_TYPE.WIFI_NETWORK.rawValue
      } else {
        self._reachabiltyNetworkType = CONNECTION_NETWORK_TYPE.WWAN_NETWORK.rawValue
      }

        } else {
            self._isReachability = false
self._reachabiltyNetworkType = CONNECTION_NETWORK_TYPE.OTHER.rawValue

        }

        NSNotificationCenter.defaultCenter().addObserver(self, selector: "reachabilityChanged:", name: ReachabilityChangedNotification, object: reachability)
    }
    func reachabilityChanged(note: NSNotification) {
        let reachability = note.object as! Reachability
        dispatch_async(dispatch_get_main_queue()) {
            if (self._useClosures) {
                self.reachability?.whenReachable = { reachability in
                    self.notifyReachability(reachability)
                }
                self.reachability?.whenUnreachable = { reachability in
                    self.notifyReachability(reachability)
                }
            } else {
                self.notifyReachability(reachability)
            }
            self.delegate?.reachabilityStatusChangeHandler(reachability)
        }
    }
    deinit {
        reachability?.stopNotifier()
        if (!_useClosures) {
            NSNotificationCenter.defaultCenter().removeObserver(self, name: ReachabilityChangedNotification, object: nil)
        }
    }
}

3)创建一个委托类。我使用委托方法来通知连接状态。

//  Protocols.swift

import Foundation
@objc protocol AppManagerDelegate:NSObjectProtocol {

    func reachabilityStatusChangeHandler(reachability:Reachability)
}

4)创建UIViewController的父类(继承方法)。父类具有所有子vc都可以访问的方法。

//  UIappViewController.swift

    import UIKit

    class UIappViewController: UIViewController,AppManagerDelegate {
        var manager:AppManager = AppManager.sharedInstance

        override func viewDidLoad() {
            super.viewDidLoad()
            manager.delegate = self
        }
        override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
        }
        func reachabilityStatusChangeHandler(reachability: Reachability) {
            if reachability.isReachable() {
                print("isReachable")
            } else {
                print("notReachable")
            }
        }
    }

5)在AppDelegate中启动实时Internet连接监控。

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

6)我已经添加了一个Swift文件名AppReference来存储常量enum值。

//  AppReference.swift

import Foundation

enum CONNECTION_NETWORK_TYPE : String {

  case WIFI_NETWORK = "Wifi"
  case WWAN_NETWORK = "Cellular"
  case OTHER = "Other"

}

7)在ViewController上(例如，你只想在网络可用的情况下调用API)

//  ViewController.swift

        import UIKit

class ViewController: UIappViewController {
  var reachability:Reachability?

  override func viewDidLoad() {
    super.viewDidLoad()
    manager.delegate = self

    if(AppManager.sharedInstance.isReachability)
    {
      print("net available")
      //call API from here.

    } else {
      dispatch_async(dispatch_get_main_queue()) {
        print("net not available")
        //Show Alert
      }
    }


    //Determine Network Type
    if(AppManager.sharedInstance.reachabiltyNetworkType == "Wifi")
    {
      print(".Wifi")
    }
    else if (AppManager.sharedInstance.reachabiltyNetworkType == "Cellular")
    {
      print(".Cellular")
    }
    else {
      dispatch_async(dispatch_get_main_queue()) {
        print("Network not reachable")
      }
    }

  }
  override func viewWillAppear(animated: Bool) {
  }
  override func didReceiveMemoryWarning() {
  }
}

样本可以在https://github.com/alvinreuben/Reachability-Sample上下载

升级到Swift 3.1- https://github.com/alvinvgeorge/Reachability-UpgradedToSwift3

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
}