思路：先获取到总的流量信息，然后用当前的总下行流量减去上一秒的下行流量得到网速！

具体实现在以下三个方法！

//获取下行速度

- (void)getByteRate {

  longlongintrate;

  longlongintcurrentBytes = [selfgetInterfaceBytes];

  if(self.lastBytes) {

  //用上当前的下行总流量减去上一秒的下行流量达到下行速录

  rate = currentBytes -self.lastBytes;

  }else{

  self.isFirstRate=NO;
}
  //保存上一秒的下行总流量
  self.lastBytes= [selfgetInterfaceBytes];

  //格式化一下
  NSString*rateStr = [selfformatNetWork:rate];

  NSLog(@"当前网速%@",rateStr);

self.playerControl.LoadingView.rateLabel.text = [NSStringstringWithFormat:@"%@",rateStr];
}

//获取数据流量详情

- (longlongint)getInterfaceBytes {

  structifaddrs*ifa_list =0, *ifa;

  if(getifaddrs(&ifa_list) == -1) {

   return 0;
  }

  uint32_tiBytes =0;//下行

  uint32_toBytes =0;//上行

  for(ifa = ifa_list; ifa; ifa = ifa->ifa_next) {

  if(AF_LINK!= ifa->ifa_addr->sa_family)

  continue;

  if(!(ifa->ifa_flags&IFF_UP) && !(ifa->ifa_flags&IFF_RUNNING))

  continue;

  if(ifa->ifa_data==0)

  continue;

  if(strncmp(ifa->ifa_name,"lo",2)) {

  structif_data*if_data = (structif_data*)ifa->ifa_data;

  iBytes += if_data->ifi_ibytes;

  oBytes += if_data->ifi_obytes;
  }
  }

  freeifaddrs(ifa_list);
  //返回下行的总流量
  returniBytes;
}

//格式化方法
- (NSString*)formatNetWork:(longlongint)rate {

  if(rate <1024) {

  return[NSStringstringWithFormat:@"%lldB/秒", rate];

  }elseif(rate >=1024&& rate <1024*1024) {

  return[NSStringstringWithFormat:@"%.1fKB/秒", (double)rate /1024];

  }elseif(rate >=1024*1024&& rate <1024*1024*1024){

  return[NSStringstringWithFormat:@"%.2fMB/秒", (double)rate / (1024*1024)];

  }else{
  return@"10Kb/秒";
};
}