Swift_Mime_Attachment::setFilename PHP Method

    public function setFilename($filename)
    {
        $this->_setHeaderParameter('Content-Disposition', 'filename', $filename);
        $this->_setHeaderParameter('Content-Type', 'name', $filename);
        return $this;
    }

 /**
  * register the new file name
  *
  * @param string $newName
  * @return $this
  */
 public function name($newName = '')
 {
     $this->attach->setFilename($newName);
     return $this;
 }