Hi,
For multiselect drop down use below code:
$selectedCategory = explode(",", $model->category_ids);
$selCategory = array();
foreach($selectedCategory as $category) {
$selCategory[$category] = array('selected'=>'selected');
}
echo CHtml::activeDropDownList($model, 'category_ids[]',
CHtml::listData($categoryList,'id', 'name'),
array(
'options' => $selCategory,
'empty'=>'Select Category',
'multiple' => 'multiple',
'size' => 10
));