判断苹果手机是否联网

-(NSString*)currntNetworkType{    NSString* result;                    Reachability *r = [Reachability reachabilityWithHostName:@"www.apple.com"];                    switch ([r currentReachabilityStatus])    {        case NotReachable:    // 没有网络连接        {            result = nil;        }            break;              case ReachableViaWWAN:// 3G        {            result = @"3G";        }            break;                                case ReachableViaWiFi:// WiFi        {            result = @"WIFI";        }            break;      }      return result;  }

调用这个方法