iOS实时监控网络状态的改变

//使用AFN框架来检测网络状态的改变
-(void)AFNReachability
{
  //1.创建网络监听管理者
  AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];

  //2.监听网络状态的改变
  /*
   AFNetworkReachabilityStatusUnknown     = 未知
   AFNetworkReachabilityStatusNotReachable   = 没有网络
   AFNetworkReachabilityStatusReachableViaWWAN = 3G
   AFNetworkReachabilityStatusReachableViaWiFi = WIFI
   */
  [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
    switch (status) {
      case AFNetworkReachabilityStatusUnknown:
        NSLog(@"未知");
        break;
      case AFNetworkReachabilityStatusNotReachable:
        NSLog(@"没有网络");
        break;
      case AFNetworkReachabilityStatusReachableViaWWAN:
        NSLog(@"3G");
        break;
      case AFNetworkReachabilityStatusReachableViaWiFi:
        NSLog(@"WIFI");
        break;

      default:
        break;
    }
  }];

  //3.开始监听
  [manager startMonitoring];
}