自定义NSURLProtocol拦截到的HTTPBody为空

由于升级AFNetWorking新版本使用了NSURLSession，老版本使用的是NSURLConnection，项目中所有POST请求拦截到的HTTPBody为空。具体解决方案如下：

    if ([req.HTTPMethod isEqualToString:@"POST"]) { 
            if (!req.HTTPBody) {  
               uint8_t rd[1024] = {0}; 
                NSInputStream *stream = request.HTTPBodyStream;
                 NSMutableData *data = [[NSMutableData alloc] init];  
               [stream open]; 
                while ([stream hasBytesAvailable]) { 
                    NSInteger len = [stream read:rd maxLength:1024];   
                  if (len > 0 && stream.streamError == nil) {   
                      [data appendBytes:(void *)rd length:len]; 
                    } 
                }     
            req.HTTPBody = [data copy]; 
                [stream close];   
          }   
      }