xml array sorteren

<?php
$xml = new SimpleXMLElement($xml_string);
$count = count($xml->website);

for( $i = 0 ; $i < $count ; $i++ ) {

	$expI = explode("-" , $xml->website[$i]->episode[0]->publish_date);
	$publish_time_i = mktime(0,0,0,$expI[1] , $expI[2] , $expI[0]);
	
	for( $j = $i+1 ; $j < $count ; $j++ ) {
	
		$expJ = explode("-" , $xml->website[$j]->episode[0]->publish_date);
		$publish_time_j = mktime(0,0,0,$expJ[1] , $expJ[2] , $expJ[0]);
		
		if( $publish_time_i < $publish_time_j ) {
			$tmp = $xml->website[$i];
			$xml->website[$i] = $xml->website[$j];
			$xml->website[$j] = $tmp;
		}
	
	}

}

<?php
$xml = new SimpleXMLElement($xml_string);
$count = count($xml->website);
 
for( $i = 0 ; $i < $count ; $i++ ) {
 
	$expI = explode("-" , $xml->website[$i]->episode[0]->publish_date);
	$publish_time_i = mktime(0,0,0,$expI[1] , $expI[2] , $expI[0]);
 
	for( $j = $i+1 ; $j < $count ; $j++ ) {
 
		$expJ = explode("-" , $xml->website[$j]->episode[0]->publish_date);
		$publish_time_j = mktime(0,0,0,$expJ[1] , $expJ[2] , $expJ[0]);
 
		if( $publish_time_i < $publish_time_j ) {
			$tmp = $xml->website[$i];
			$xml->website[$i] = $xml->website[$j];
			$xml->website[$j] = $tmp;
		}
 
	}
 
}