Force group / sort Joomla items by category

gistfile1.phtml

<?php
$db    = JFactory::getDbo();
$query = $db->getQuery(true);
$query->select($db->quoteName(array('id')))
	->from($db->quoteName('#__categories'))
	->where($db->quoteName('published') . ' = ' . $db->quote('1') .
		' AND ' . $db->quoteName('extension') . ' = ' . $db->quote('com_content'))
	->order('LFT ASC');
$db->setQuery($query);
$categories = $db->loadObjectList('id');

foreach ($categories as $category)
{
	foreach ($this->intro_items as $key => $intro_item)
	{
		if ($intro_item->catid == $category->id)
		{
			$this->intro_items[] = $intro_item;
			unset ($this->intro_items[$key]);
		}
	}
}