转自：http://blog.csdn.net/lwq421336220/article/details/16982857

- (BOOL) connectedToNetwork

{

    //创建零地址，0.0.0.0的地址表示查询本机的网络连接状态

   structsockaddr_in zeroAddress;

   bzero(&zeroAddress,sizeof(zeroAddress));

    zeroAddress.sin_len =sizeof(zeroAddress);

    zeroAddress.sin_family =AF_INET;

    

    

   SCNetworkReachabilityRef defaultRouteReachability =SCNetworkReachabilityCreateWithAddress(NULL, (structsockaddr *)&zeroAddress);

    SCNetworkReachabilityFlags flags;

    

   BOOL didRetrieveFlags =SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);

   CFRelease(defaultRouteReachability);

    

   if (!didRetrieveFlags)

    {

        printf("Error. Could not recover network reachability flagsn");

       returnNO;

    }

    

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

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

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

}

使用的时候：

 

if ([selfconnectedToNetwork]) {

        

}else{

   UIAlertView *alert=[[UIAlertViewalloc]initWithTitle:@"提示" message:@"网络连接失败，请查看网络连接。" delegate:self cancelButtonTitle:@"我知道了" otherButtonTitles:nil,nil];

   [alertshow];

        

        

}