code: public function saveAs($file, $deleteTempFile = true)
      {
          if ($this->error == UPLOAD_ERR_OK) {
              if ($deleteTempFile) {
                  return move_uploaded_file($this->tempName, $file);
              } elseif (is_uploaded_file($this->tempName)) {
                  return copy($this->tempName, $file);
              }
          }
  
          return false;
      }
docs: Saves the uploaded file.
  Note that this method uses php's move_uploaded_file() method. If the target file `$file`
  already exists, it will be overwritten.
  @param string $file the file path used to save the uploaded file
  @param bool $deleteTempFile whether to delete the temporary file after saving.
  If true, you will not be able to save the uploaded file again in the current request.
  @return bool true whether the file is saved successfully
  @see error