How do I set an option in a dropdown attribute as the default? I am adding the options to an existing attribute with this code where $aName is an array of names. 

    $installer = new Mage_Eav_Model_Entity_Setup('core_setup');
	$installer->startSetup();
	$aName = array("Name1", "Name2");

	$aOption = array();
	$aOption['attribute_id'] = $attr_id; 

	for($iCount=1;$iCount<sizeof($aName);$iCount++){
		   	$aOption['value']['option'.$iCount][0] = $aName[$iCount];	
            $aOption['order']['option'.$iCount] = $iCount	;  
	}
	
	$installer->addAttributeOption($aOption);
	$installer->endSetup();

I think the answer is in Stackoverflow [here][1] but I don't know how to apply it. In my case the Attribute exists, I'm just updating the option list and setting the default.





  [1]: http://magento.stackexchange.com/questions/29724/adding-a-product-attribute-with-values-and-mark-one-value-as-default