In the original the attached filename contained the path (prepended) with slashed replaced by underscores so I modded the code to;

$onlyfilename = basename($filename);
$this->attachment[] = array(
0 => $string,
1 => $filename,
2 => $onlyfilename,
3 => $encoding,
4 => $type,
5 => true, // isStringAttachment
6 => ‘inline’,
7 => $cid
);