generate unique alias

$doc = $this->modx->newObject('modResource');
$alias = $doc->cleanAlias($pagetitle);

if($this->modx->getCount('modResource', array('alias'=>$alias))!= 0) {
$count = 1;
$newAlias = $alias;
while($this->modx->getCount('modResource', array('alias'=>$newAlias))!= 0) {
$newAlias = $alias;
$newAlias .= '-' . $count;
$count++;
}
$alias = $newAlias;
}