压缩图片到指定大小

/**

• 压缩图片到指定文件大小
• @param image 目标图片
• @param size 目标大小（最大值），例如最大2M，就传2.0
• @return 返回的图片文件
  */

• (NSData *)compressOriginalImage:(UIImage *)image toMaxDataSizeKBytes:(CGFloat)size {
  NSData * data = UIImageJPEGRepresentation(image, 1.0);
  CGFloat dataKBytes = data.length/1000.0;
  CGFloat maxQuality = size-0.01;
  CGFloat lastData = dataKBytes;
  while (dataKBytes > size && maxQuality > 0.01f) {
  maxQuality = maxQuality - 0.01f;
  data = UIImageJPEGRepresentation(image, maxQuality);
  dataKBytes = data.length / 1000.0;
  if (lastData == dataKBytes) {
  break;
  }else{
  lastData = dataKBytes;
  }
  }
  return data;
  }