Apple 提供了一个示例应用，它完全可以做到这一点：

可达性

Apple 提供了示例代码来检查不同类型的网络可用性。另外，iPhone 开发人员食谱中有一个示例。

注意：请参阅@KHG对此答案中关于使用 Apple 可访问性代码的评论。

这曾经是正确的答案，但现在已经过时了，因为您应该订阅可访问性通知。此方法同步检查：

---

您可以使用 Apple 的 Reachability 类。它还允许您检查是否启用了 Wi-Fi：

Reachability* reachability = [Reachability sharedReachability];
[reachability setHostName:@"www.example.com"];    // Set your host name here
NetworkStatus remoteHostStatus = [reachability remoteHostStatus];

if (remoteHostStatus == NotReachable) { }
else if (remoteHostStatus == ReachableViaWiFiNetwork) { }
else if (remoteHostStatus == ReachableViaCarrierDataNetwork) { }

Reachability 类不随 SDK 一起提供，而是此 Apple 示例应用程序的一部分。只需下载它，并将 Reachability.h/m 复制到您的项目中。此外，还必须将 SystemConfiguration 框架添加到项目中。

仅更新了 Reachability 类。您现在可以使用：

Reachability* reachability = [Reachability reachabilityWithHostName:@"www.apple.com"];
NetworkStatus remoteHostStatus = [reachability currentReachabilityStatus];

if (remoteHostStatus == NotReachable) { NSLog(@"not reachable");}
else if (remoteHostStatus == ReachableViaWWAN) { NSLog(@"reachable via wwan");}
else if (remoteHostStatus == ReachableViaWiFi) { NSLog(@"reachable via wifi");}

重要提示：此检查应始终异步执行。下面的大多数答案都是同步的，所以要小心，否则你会冻结你的应用程序。

---

迅速

1. 通过 CocoaPods 或 Carthage 安装：https://github.com/ashleymills/Reachability.swift

2. 通过闭包测试可达性

   let reachability = Reachability()!
   
   reachability.whenReachable = { reachability in
       if reachability.connection == .wifi {
           print("Reachable via WiFi")
       } else {
           print("Reachable via Cellular")
       }
   }
   
   reachability.whenUnreachable = { _ in
       print("Not reachable")
   }
   
   do {
       try reachability.startNotifier()
   } catch {
       print("Unable to start notifier")
   }
   

---

Objective-C语言

1. 将框架添加到项目中，但不要担心将其包含在任何地方SystemConfiguration

2. 将 Tony Million 的 和 版本添加到项目中（可在此处找到：https://github.com/tonymillion/ReachabilityReachability.hReachability.m)

3. 更新接口部分

   #import "Reachability.h"
   
   // Add this to the interface in the .m file of your view controller
   @interface MyViewController ()
   {
       Reachability *internetReachableFoo;
   }
   @end
   

4. 然后在视图控制器的 .m 文件中实现此方法，您可以调用该方法

   // Checks if we have an internet connection or not
   - (void)testInternetConnection
   {
       internetReachableFoo = [Reachability reachabilityWithHostname:@"www.google.com"];
   
       // Internet is reachable
       internetReachableFoo.reachableBlock = ^(Reachability*reach)
       {
           // Update the UI on the main thread
           dispatch_async(dispatch_get_main_queue(), ^{
               NSLog(@"Yayyy, we have the interwebs!");
           });
       };
   
       // Internet is not reachable
       internetReachableFoo.unreachableBlock = ^(Reachability*reach)
       {
           // Update the UI on the main thread
           dispatch_async(dispatch_get_main_queue(), ^{
               NSLog(@"Someone broke the internet :(");
           });
       };
   
       [internetReachableFoo startNotifier];
   }
   

重要提示：该类是项目中最常用的类之一，因此可能会遇到与其他项目的命名冲突。如果发生这种情况，您必须将其中一对 and 文件重命名为其他名称才能解决问题。ReachabilityReachability.hReachability.m

注意：您使用的域无关紧要。它只是测试任何域的网关。

我喜欢让事情变得简单。我这样做的方法是：

//Class.h
#import "Reachability.h"
#import <SystemConfiguration/SystemConfiguration.h>

- (BOOL)connected;

//Class.m
- (BOOL)connected
{
    Reachability *reachability = [Reachability reachabilityForInternetConnection];
    NetworkStatus networkStatus = [reachability currentReachabilityStatus];
    return networkStatus != NotReachable;
}

然后，每当我想查看我是否有连接时，我都会使用它：

if (![self connected]) {
    // Not connected
} else {
    // Connected. Do some Internet stuff
}

此方法不会等待更改的网络状态来执行操作。它只是在你要求它时测试状态。

使用 Apple 的 Reachability 代码，我创建了一个函数，该函数可以正确检查这一点，而无需包含任何类。

在项目中包括 SystemConfiguration.framework。

进行一些导入：

#import <sys/socket.h>
#import <netinet/in.h>
#import <SystemConfiguration/SystemConfiguration.h>

现在只需调用此函数：

/*
Connectivity testing code pulled from Apple's Reachability Example: https://developer.apple.com/library/content/samplecode/Reachability
 */
+(BOOL)hasConnectivity {
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr*)&zeroAddress);
    if (reachability != NULL) {
        //NetworkStatus retVal = NotReachable;
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(reachability, &flags)) {
            if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
            {
                // If target host is not reachable
                return NO;
            }

            if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
            {
                // If target host is reachable and no connection is required
                //  then we'll assume (for now) that your on Wi-Fi
                return YES;
            }


            if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) ||
                 (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
            {
                // ... and the connection is on-demand (or on-traffic) if the
                //     calling application is using the CFSocketStream or higher APIs.

                if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
                {
                    // ... and no [user] intervention is needed
                    return YES;
                }
            }

            if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)
            {
                // ... but WWAN connections are OK if the calling application
                //     is using the CFNetwork (CFSocketStream?) APIs.
                return YES;
            }
        }
    }

    return NO;
}

它经过了 iOS 5 测试。

您可以通过  使用（可在此处获得）。Reachability

#import "Reachability.h"

- (BOOL)networkConnection {
    return [[Reachability reachabilityWithHostName:@"www.google.com"] currentReachabilityStatus];
}

if ([self networkConnection] == NotReachable) { /* No Network */ } else { /* Network */ } //Use ReachableViaWiFi / ReachableViaWWAN to get the type of connection.

这是一个非常简单的答案：

NSURL *scriptUrl = [NSURL URLWithString:@"http://www.google.com/m"];
NSData *data = [NSData dataWithContentsOfURL:scriptUrl];
if (data)
    NSLog(@"Device is connected to the Internet");
else
    NSLog(@"Device is not connected to the Internet");

该 URL 应指向一个非常小的网站。我在这里使用谷歌的移动网站，但如果我有可靠的网络服务器，我会上传一个小文件，里面只有一个字符，以获得最大速度。

如果检查设备是否以某种方式连接到互联网是您想要做的一切，我绝对建议您使用这个简单的解决方案。如果您需要了解用户是如何连接的，那么使用可访问性是要走的路。

小心：这将在加载网站时短暂阻止您的线程。就我而言，这不是问题，但你应该考虑这一点（感谢布拉德指出这一点）。

- (void)viewWillAppear:(BOOL)animated
{
    NSString *URL = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://www.google.com"]];

    return (URL != NULL ) ? YES : NO;
}

或者使用 Reachability 类。

有两种方法可以使用 iPhone SDK 检查互联网可用性：

1.检查Google页面是否打开。

2. 可达性类

有关详细信息，请参阅可访问性 （Apple Developer）。

以下是我在我的应用程序中如何做到这一点： 虽然 200 状态响应代码不能保证任何事情，但它对我来说足够稳定。这不需要像此处发布的 NSData 答案那样多的加载，因为我只需要检查 HEAD 响应。

SWIFT代码

func checkInternet(flag:Bool, completionHandler:(internet:Bool) -> Void)
{
    UIApplication.sharedApplication().networkActivityIndicatorVisible = true

    let url = NSURL(string: "http://www.google.com/")
    let request = NSMutableURLRequest(URL: url!)

    request.HTTPMethod = "HEAD"
    request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalAndRemoteCacheData
    request.timeoutInterval = 10.0

    NSURLConnection.sendAsynchronousRequest(request, queue:NSOperationQueue.mainQueue(), completionHandler:
    {(response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in

        UIApplication.sharedApplication().networkActivityIndicatorVisible = false

        let rsp = response as! NSHTTPURLResponse?

        completionHandler(internet:rsp?.statusCode == 200)
    })
}

func yourMethod()
{
    self.checkInternet(false, completionHandler:
    {(internet:Bool) -> Void in

        if (internet)
        {
            // "Internet" aka Google URL reachable
        }
        else
        {
            // No "Internet" aka Google URL un-reachable
        }
    })
}

Objective-C 代码

typedef void(^connection)(BOOL);

- (void)checkInternet:(connection)block
{
    NSURL *url = [NSURL URLWithString:@"http://www.google.com/"];
    NSMutableURLRequest *headRequest = [NSMutableURLRequest requestWithURL:url];
    headRequest.HTTPMethod = @"HEAD";

    NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration ephemeralSessionConfiguration];
    defaultConfigObject.timeoutIntervalForResource = 10.0;
    defaultConfigObject.requestCachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;

    NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration:defaultConfigObject delegate:self delegateQueue: [NSOperationQueue mainQueue]];

    NSURLSessionDataTask *dataTask = [defaultSession dataTaskWithRequest:headRequest
        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error)
    {
        if (!error && response)
        {
            block([(NSHTTPURLResponse *)response statusCode] == 200);
        }
    }];
    [dataTask resume];
}

- (void)yourMethod
{
    [self checkInternet:^(BOOL internet)
    {
         if (internet)
         {
             // "Internet" aka Google URL reachable
         }
         else
         {
             // No "Internet" aka Google URL un-reachable
         }
    }];
}

如果您使用的是 AFNetworking，则可以使用其自己的实现来获取 Internet 可访问性状态。

最好的使用方法是将类子类化，并使用此类进行网络连接。AFNetworkingAFHTTPClient

使用此方法的优点之一是，当可访问性状态更改时，可以使用此方法设置所需的行为。假设我已经创建了一个名为 的单例子类（如 AFNetworking 文档上的“子类注释”中所述），我会做这样的事情：blocksAFHTTPClientBKHTTPClient

BKHTTPClient *httpClient = [BKHTTPClient sharedClient];
[httpClient setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status)
{
    if (status == AFNetworkReachabilityStatusNotReachable) 
    {
    // Not reachable
    }
    else
    {
        // Reachable
    }
}];

您还可以专门使用 和 枚举检查 Wi-Fi 或 WLAN 连接（更多内容在这里）。AFNetworkReachabilityStatusReachableViaWWANAFNetworkReachabilityStatusReachableViaWiFi

-(void)newtworkType {

 NSArray *subviews = [[[[UIApplication sharedApplication] valueForKey:@"statusBar"] valueForKey:@"foregroundView"]subviews];
NSNumber *dataNetworkItemView = nil;

for (id subview in subviews) {
    if([subview isKindOfClass:[NSClassFromString(@"UIStatusBarDataNetworkItemView") class]]) {
        dataNetworkItemView = subview;
        break;
    }
}


switch ([[dataNetworkItemView valueForKey:@"dataNetworkType"]integerValue]) {
    case 0:
        NSLog(@"No wifi or cellular");
        break;

    case 1:
        NSLog(@"2G");
        break;

    case 2:
        NSLog(@"3G");
        break;

    case 3:
        NSLog(@"4G");
        break;

    case 4:
        NSLog(@"LTE");
        break;

    case 5:
        NSLog(@"Wifi");
        break;


    default:
        break;
}
}

首先下载 reachability 类，并将 reachability.h 和 reachabilty.m 文件放入 Xcode 中。

最好的方法是创建一个通用的 Functions 类 （NSObject），以便您可以在任何类中使用它。以下是网络连接可访问性检查的两种方法：

+(BOOL) reachabiltyCheck
{
    NSLog(@"reachabiltyCheck");
    BOOL status =YES;
    [[NSNotificationCenter defaultCenter] addObserver:self
                                          selector:@selector(reachabilityChanged:)
                                          name:kReachabilityChangedNotification
                                          object:nil];
    Reachability * reach = [Reachability reachabilityForInternetConnection];
    NSLog(@"status : %d",[reach currentReachabilityStatus]);
    if([reach currentReachabilityStatus]==0)
    {
        status = NO;
        NSLog(@"network not connected");
    }
    reach.reachableBlock = ^(Reachability * reachability)
    {
        dispatch_async(dispatch_get_main_queue(), ^{
        });
    };
    reach.unreachableBlock = ^(Reachability * reachability)
    {
        dispatch_async(dispatch_get_main_queue(), ^{
        });
    };
    [reach startNotifier];
    return status;
}

+(BOOL)reachabilityChanged:(NSNotification*)note
{
    BOOL status =YES;
    NSLog(@"reachabilityChanged");
    Reachability * reach = [note object];
    NetworkStatus netStatus = [reach currentReachabilityStatus];
    switch (netStatus)
    {
        case NotReachable:
            {
                status = NO;
                NSLog(@"Not Reachable");
            }
            break;

        default:
            {
                if (!isSyncingReportPulseFlag)
                {
                    status = YES;
                    isSyncingReportPulseFlag = TRUE;
                    [DatabaseHandler checkForFailedReportStatusAndReSync];
                }
            }
            break;
    }
    return status;
}

+ (BOOL) connectedToNetwork
{
    // Create zero addy
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    // Recover reachability flags
    SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
    SCNetworkReachabilityFlags flags;
    BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
    CFRelease(defaultRouteReachability);
    if (!didRetrieveFlags)
    {
        NSLog(@"Error. Could not recover network reachability flags");
        return NO;
    }
    BOOL isReachable = flags & kSCNetworkFlagsReachable;
    BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
    BOOL nonWiFi = flags & kSCNetworkReachabilityFlagsTransientConnection;
    NSURL *testURL = [NSURL URLWithString:@"http://www.apple.com/"];
    NSURLRequest *testRequest = [NSURLRequest requestWithURL:testURL  cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:20.0];
    NSURLConnection *testConnection = [[NSURLConnection alloc] initWithRequest:testRequest delegate:self];
    return ((isReachable && !needsConnection) || nonWiFi) ? (testConnection ? YES : NO) : NO;
}

现在，您可以通过调用此类方法检查任何类中的网络连接。

Reachability 类可以确定 Internet 连接是否可用于设备...

但是，在访问 Intranet 资源的情况下：

使用 reachability 类对 Intranet 服务器执行 ping 操作始终返回 true。

因此，在此方案中，一个快速的解决方案是创建一个 Web 方法，该方法与服务上的其他 Web 方法一起调用。 应该返回一些东西。pingmepingme

所以我写了下面关于常用函数的方法

-(BOOL)PingServiceServer
{
    NSURL *url=[NSURL URLWithString:@"http://www.serveraddress/service.asmx/Ping"];

    NSMutableURLRequest *urlReq=[NSMutableURLRequest requestWithURL:url];

    [urlReq setTimeoutInterval:10];

    NSURLResponse *response;

    NSError *error = nil;

    NSData *receivedData = [NSURLConnection sendSynchronousRequest:urlReq
                                                 returningResponse:&response
                                                             error:&error];
    NSLog(@"receivedData:%@",receivedData);

    if (receivedData !=nil)
    {
        return YES;
    }
    else
    {
        NSLog(@"Data is null");
        return NO;
    }
}

上述方法对我来说非常有用，因此每当我尝试向服务器发送一些数据时，我总是使用这个低超时 URLRequest 检查我的 Intranet 资源的可访问性。

从 https://github.com/tonymillion/Reachability 获取 Reachabilty 类，在项目中添加系统配置框架，在类中导入 Reachability.h 并实现自定义方法，如下所示：

- (BOOL)isConnectedToInternet
{
    //return NO; // Force for offline testing
    Reachability *hostReach = [Reachability reachabilityForInternetConnection];
    NetworkStatus netStatus = [hostReach currentReachabilityStatus];
    return !(netStatus == NotReachable);
}

在 中导入类，并使用以下代码检查连通性：Reachable.hViewController

#define hasInternetConnection [[Reachability reachabilityForInternetConnection] isReachable]
if (hasInternetConnection){
      // To-do block
}

还有另一种使用 iPhone SDK 检查 Internet 连接的方法。

尝试为网络连接实现以下代码。

#import <SystemConfiguration/SystemConfiguration.h>
#include <netdb.h>

/**
     Checking for network availability. It returns
     YES if the network is available.
*/
+ (BOOL) connectedToNetwork
{

    // Create zero addy
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    // Recover reachability flags
    SCNetworkReachabilityRef defaultRouteReachability =
        SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
    SCNetworkReachabilityFlags flags;

    BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
    CFRelease(defaultRouteReachability);

    if (!didRetrieveFlags)
    {
        printf("Error. Could not recover network reachability flags\n");
        return NO;
    }

    BOOL isReachable = ((flags & kSCNetworkFlagsReachable) != 0);
    BOOL needsConnection = ((flags & kSCNetworkFlagsConnectionRequired) != 0);

    return (isReachable && !needsConnection) ? YES : NO;
}

自己做这件事非常简单。以下方法将起作用。只要确保不允许将主机名协议（如 HTTP、HTTPS 等）与名称一起传入即可。

-(BOOL)hasInternetConnection:(NSString*)urlAddress
{
    SCNetworkReachabilityRef ref = SCNetworkReachabilityCreateWithName(kCFAllocatorDefault, [urlAddress UTF8String]);
    SCNetworkReachabilityFlags flags;
    if (!SCNetworkReachabilityGetFlags(ref, &flags))
    {
        return NO;
    }
    return flags & kSCNetworkReachabilityFlagsReachable;
}

它快速、简单且无痛。

第一：在框架中添加CFNetwork.framework

代码：ViewController.m

#import "Reachability.h"

- (void)viewWillAppear:(BOOL)animated
{
    Reachability *r = [Reachability reachabilityWithHostName:@"www.google.com"];
    NetworkStatus internetStatus = [r currentReachabilityStatus];

    if ((internetStatus != ReachableViaWiFi) && (internetStatus != ReachableViaWWAN))
    {
        /// Create an alert if connection doesn't work
        UIAlertView *myAlert = [[UIAlertView alloc]initWithTitle:@"No Internet Connection"   message:NSLocalizedString(@"InternetMessage", nil)delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [myAlert show];
        [myAlert release];
    }
    else
    {
         NSLog(@"INTERNET IS CONNECT");
    }
}

很简单......请尝试以下步骤：

步骤1：将框架添加到项目中。SystemConfiguration

---

步骤2：将以下代码导入到文件中。header

#import <SystemConfiguration/SystemConfiguration.h>

---

步骤3：使用以下方法

• 类型 1：

  - (BOOL) currentNetworkStatus {
      [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
      BOOL connected;
      BOOL isConnected;
      const char *host = "www.apple.com";
      SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, host);
      SCNetworkReachabilityFlags flags;
      connected = SCNetworkReachabilityGetFlags(reachability, &flags);
      isConnected = NO;
      isConnected = connected && (flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired);
      CFRelease(reachability);
      return isConnected;
  }
  

---

• 类型 2：

  导入标题 ：#import "Reachability.h"

  - (BOOL)currentNetworkStatus
  {
      Reachability *reachability = [Reachability reachabilityForInternetConnection];
      NetworkStatus networkStatus = [reachability currentReachabilityStatus];
      return networkStatus != NotReachable;
  }
  

---

步骤4：如何使用：

- (void)CheckInternet
{
    BOOL network = [self currentNetworkStatus];
    if (network)
    {
        NSLog(@"Network Available");
    }
    else
    {
        NSLog(@"No Network Available");
    }
}

导入 “Reachability.h”

-(BOOL)netStat
{
    Reachability *test = [Reachability reachabilityForInternetConnection];
    return [test isReachable];
}

我认为这是最好的答案。

“是”表示已连接。“否”表示断开连接。

#import "Reachability.h"

 - (BOOL)canAccessInternet
{
    Reachability *IsReachable = [Reachability reachabilityForInternetConnection];
    NetworkStatus internetStats = [IsReachable currentReachabilityStatus];

    if (internetStats == NotReachable)
    {
        return NO;
    }
    else
    {
        return YES;
    }
}

1. 下载可访问性文件，https://gist.github.com/darkseed/1182373

2. 并在框架中添加和“SystemConfiguration.framework”CFNetwork.framework

3. #import“Reachability.h”

第一：在框架中添加CFNetwork.framework

代码：ViewController.m

- (void)viewWillAppear:(BOOL)animated
{
    Reachability *r = [Reachability reachabilityWithHostName:@"www.google.com"];
    NetworkStatus internetStatus = [r currentReachabilityStatus];

    if ((internetStatus != ReachableViaWiFi) && (internetStatus != ReachableViaWWAN))
    {
        /// Create an alert if connection doesn't work
        UIAlertView *myAlert = [[UIAlertView alloc]initWithTitle:@"No Internet Connection"   message:NSLocalizedString(@"InternetMessage", nil)delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [myAlert show];
        [myAlert release];
    }
    else
    {
         NSLog(@"INTERNET IS CONNECT");
    }
}

创建一个对象，并使用以下代码来跟踪网络连接AFNetworkReachabilityManager

self.reachabilityManager = [AFNetworkReachabilityManager managerForDomain:@"yourDomain"];
[self.reachabilityManager startMonitoring];
[self.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
        switch (status) {
            case AFNetworkReachabilityStatusReachableViaWWAN:
            case AFNetworkReachabilityStatusReachableViaWiFi:
                break;
            case AFNetworkReachabilityStatusNotReachable:
                break;
            default:
                break;
        }
    }];

• 第 1 步：在项目中添加 Reachability 类。
• 步骤 2：导入 Reachability 类

• 第 3 步：创建以下函数

  - (BOOL)checkNetConnection {
      self.internetReachability = [Reachability reachabilityForInternetConnection];
      [self.internetReachability startNotifier];
      NetworkStatus netStatus = [self.internetReachability currentReachabilityStatus];
      switch (netStatus) {
          case NotReachable:
          {
              return NO;
          }
  
          case ReachableViaWWAN:
          {
               return YES;
          }
  
          case ReachableViaWiFi:
          {
               return YES;
          }
      }
  }
  

• 第 4 步：按如下方式调用函数：

  if (![self checkNetConnection]) {
      [GlobalFunctions showAlert:@""
                       message:@"Please connect to the Internet!"
                       canBtntitle:nil
                       otherBtnTitle:@"Ok"];
      return;
  }
  else
  {
      Log.v("internet is connected","ok");
  }
  

在 （iOS） Xcode 8 和 Swift 3.0 中检查 Internet 连接可用性

这是检查网络可用性的简单方法，例如我们的设备是否连接到任何网络。我已经设法将其翻译成 Swift 3.0 和最终代码。现有的 Apple Reachability 类和其他第三方库似乎太复杂了，无法转换为 Swift。

这适用于 3G、4G 和 WiFi 连接。

不要忘记将“SystemConfiguration.framework”添加到您的项目构建器中。

//Create new swift class file Reachability in your project.
import SystemConfiguration
public class InternetReachability {

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(nil, UnsafePointer($0)).takeRetainedValue()
   }
   var flags: SCNetworkReachabilityFlags = 0
   if SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) == 0 {
          return false
   }
   let isReachable = (flags & UInt32(kSCNetworkFlagsReachable)) != 0
   let needsConnection = (flags & UInt32(kSCNetworkFlagsConnectionRequired)) != 0

   return isReachable && !needsConnection
  }
}

// Check network connectivity from anywhere in project by using this code.
 if InternetReachability.isConnectedToNetwork() == true {
         print("Internet connection OK")
  } else {
         print("Internet connection FAILED")
  }

这适用于 Swift 3.0 和异步。大多数答案是同步解决方案，如果您的连接速度非常慢，它将阻止您的主线程。

这个解决方案更好，但并不完美，因为它依靠 Google 来检查连接性，因此请随意使用另一个 URL。

func checkInternetConnection(completionHandler:@escaping (Bool) -> Void)
{
    if let url = URL(string: "http://www.google.com/")
    {
        var request = URLRequest(url: url)
        request.httpMethod = "HEAD"
        request.cachePolicy = .reloadIgnoringLocalAndRemoteCacheData
        request.timeoutInterval = 5

        let tast = URLSession.shared.dataTask(with: request, completionHandler:
        {
            (data, response, error) in

            completionHandler(error == nil)
        })
        tast.resume()
    }
    else
    {
        completionHandler(true)
    }
}

试试这个：

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error


if ([self.delegate respondsToSelector:@selector(getErrorResponse:)]) {
    [self.delegate performSelector:@selector(getErrorResponse:) withObject:@"No Network Connection"];
}

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"BMC" message:@"No Network Connection" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK",nil];
[alertView show];

}

斯威夫特 3 / 斯威夫特 4

您必须先导入

import SystemConfiguration

您可以使用以下方法检查 Internet 连接：

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)
}

阿拉莫火

我知道这个问题是要求 Coca Touch 解决方案，但我想为在 iOS 上搜索检查 Internet 连接的人提供一个解决方案，并且在这里还有一个选择。

如果您已经在使用 Alamofire，那么您可以从中受益。

可以将以下类添加到应用，并调用以获取有关它是否已连接的布尔值。MNNetworkUtils.main.isConnected()

#import Alamofire

class MNNetworkUtils {
  static let main = MNNetworkUtils()
  init() {
    manager = NetworkReachabilityManager(host: "google.com")
    listenForReachability()
  }

  private let manager: NetworkReachabilityManager?
  private var reachable: Bool = false
  private func listenForReachability() {
    self.manager?.listener = { [unowned self] status in
      switch status {
      case .notReachable:
        self.reachable = false
      case .reachable(_), .unknown:
        self.reachable = true
      }
    }
    self.manager?.startListening()
  }

  func isConnected() -> Bool {
    return reachable
  }
}

这是一个单例类。每次，当用户连接或断开网络时，它都会正确地覆盖到 true/false，因为我们开始监听 on 单例初始化。self.reachableNetworkReachabilityManager

此外，为了监视可访问性，您需要提供主机。目前，我正在使用 google.com，但如果需要，请随时更改为任何其他主机或您的主机之一。将类名和文件名更改为与项目匹配的任何名称。

使用 Xcode 9 和 Swift 4.0 在 （iOS） 中检查 Internet 连接可用性

请按照以下步骤操作

步骤1：

创建一个扩展文件，并将其命名为 ReachabilityManager.swift。然后添加下面的代码行。

import Foundation
import SystemConfiguration
public class ConnectionCheck
{
    class func isConnectedToNetwork() -> Bool
    {
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
        zeroAddress.sin_family = sa_family_t(AF_INET)

        guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress,
        {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                SCNetworkReachabilityCreateWithAddress(nil, $0)
            }
        })
        else {
            return false
        }

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

        let isReachable = flags.contains(.reachable)
        let needsConnection = flags.contains(.connectionRequired)

        return (isReachable && !needsConnection)
    }
}

步骤2：使用下面的代码调用上面的扩展。

if ConnectionCheck.isConnectedToNetwork()
{
     print("Connected")
     // Online related Business logic
}
else{
     print("disConnected")
     // Offline related business logic
}

Pod `Alamofire` has `NetworkReachabilityManager`, you just have to create one function 

func isConnectedToInternet() ->Bool {
        return NetworkReachabilityManager()!.isReachable
}

对于我的 iOS 项目，我建议使用

可访问性类

在 Swift 中声明。对我来说，它工作得很好

Wi-Fi 和蜂窝移动数据

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
        }

        let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        let ret = (isReachable && !needsConnection)
        return ret
    }
}

使用条件语句，

if Reachability.isConnectedToNetwork() {
    // Enter your code here
}
}
else {
    print("NO Internet connection")
}

此类在应用使用 Internet 连接的几乎所有情况下都很有用。 例如，如果条件为真，则可以调用 API 或执行任务。

请试试这个。它会帮助你 （Swift 4）

1. 通过 CocoaPods 或 Carthage 安装 Reachability：可访问性

2. 导入 Reachability 并在 Network 类中使用它

   import Reachability
   
   class Network {
   
      private let internetReachability : Reachability?
      var isReachable : Bool = false
   
      init() {
   
          self.internetReachability = Reachability.init()
          do{
              try self.internetReachability?.startNotifier()
              NotificationCenter.default.addObserver(self, selector: #selector(self.handleNetworkChange), name: .reachabilityChanged, object: internetReachability)
          }
          catch {
           print("could not start reachability notifier")
          }
      }
   
      @objc private func handleNetworkChange(notify: Notification) {
   
          let reachability = notify.object as! Reachability
          if reachability.connection != .none {
              self.isReachable = true
          }
          else {
              self.isReachable = false
          }
          print("Internet Connected : \(self.isReachable)") //Print Status of Network Connection
      }
   }
   

3. 在您需要的地方使用如下。

   var networkOBJ = Network()
   // Use "networkOBJ.isReachable" for Network Status
   print(networkOBJ.isReachable)
   

//
//  Connectivity.swift
// 
//
//  Created by Kausik Jati on 17/07/20.
// 
//

import Foundation
import Network

enum ConnectionState: String {
    case notConnected = "Internet connection not avalable"
    case connected = "Internet connection avalable"
    case slowConnection = "Internet connection poor"
}
protocol ConnectivityDelegate: class {
    func checkInternetConnection(_ state: ConnectionState, isLowDataMode: Bool)
}
class Connectivity: NSObject {
    private let monitor = NWPathMonitor()
    weak var delegate: ConnectivityDelegate? = nil
    private let queue = DispatchQueue.global(qos: .background)
    private var isLowDataMode = false
    static let instance = Connectivity()
private override init() {
    super.init()
    monitor.start(queue: queue)
    startMonitorNetwork()
}
private func startMonitorNetwork() {
    monitor.pathUpdateHandler = { path in
        if #available(iOS 13.0, *) {
            self.isLowDataMode = path.isConstrained
        } else {
            // Fallback on earlier versions
            self.isLowDataMode = false
        }
        
        if path.status == .requiresConnection {
            print("requiresConnection")
                self.delegate?.checkInternetConnection(.slowConnection, isLowDataMode: self.isLowDataMode)
        } else if path.status == .satisfied {
            print("satisfied")
                 self.delegate?.checkInternetConnection(.connected, isLowDataMode: self.isLowDataMode)
        } else if path.status == .unsatisfied {
            print("unsatisfied")
                self.delegate?.checkInternetConnection(.notConnected, isLowDataMode: self.isLowDataMode)
            }
        }
    
    }
    func stopMonitorNetwork() {
        monitor.cancel()
    }
}

Swift 5，Alamofire，主机

// Session reference
var alamofireSessionManager: Session!

func checkHostReachable(completionHandler: @escaping (_ isReachable:Bool) -> Void) {
    let configuration = URLSessionConfiguration.default
    configuration.timeoutIntervalForRequest = 1
    configuration.timeoutIntervalForResource = 1
    configuration.requestCachePolicy = .reloadIgnoringLocalCacheData

    alamofireSessionManager = Session(configuration: configuration)

    alamofireSessionManager.request("https://google.com").response { response in
        completionHandler(response.response?.statusCode == 200)
    }
}

// Using
checkHostReachable() { (isReachable) in
    print("isReachable:\(isReachable)")
}

使用 iOS 12 或 macOS v10.14 （Mojave） 或更高版本时，您可以使用代替史前类。作为奖励，您可以轻松检测当前的网络连接类型：NWPathMonitorReachability

import Network // Put this on top of your class

let monitor = NWPathMonitor()

monitor.pathUpdateHandler = { path in
    if path.status != .satisfied {
        // Not connected
    }
    else if path.usesInterfaceType(.cellular) {
        // Cellular 3/4/5g connection
    }
    else if path.usesInterfaceType(.wifi) {
        // Wi-Fi connection
    }
    else if path.usesInterfaceType(.wiredEthernet) {
        // Ethernet connection
    }
}

monitor.start(queue: DispatchQueue.global(qos: .background))

更多信息在这里： https://developer.apple.com/documentation/network/nwpathmonitor

Swift 5 及更高版本：

public class Reachability {
    class func isConnectedToNetwork() -> Bool {
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
        zeroAddress.sin_family = sa_family_t(AF_INET)

        guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress, {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                SCNetworkReachabilityCreateWithAddress(nil, $0)
            }
        }) else {
            return false
        }

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

        let isReachable = flags.contains(.reachable)
        let needsConnection = flags.contains(.connectionRequired)

        return (isReachable && !needsConnection)
    }

像这样调用这个类：

if Reachability.isConnectedToNetwork() == true {
    // Do something
} else {
    // Do something
}