public function saveSorting()
 {
     if (count($_POST['sorting'])) {
         foreach ($_POST['sorting'] as $topic_id => $sorting_value) {
             $oTopic = new ilShopTopic($topic_id);
             $oTopic->setCustomSorting((int) $sorting_value);
             $oTopic->saveCustomSorting();
         }
     }
     ilUtil::sendInfo($this->lng->txt('saved_successfully'));
     return $this->showTopicsSortingTable();
 }