EntityCollection::getItemByIndex

public function getItemByIndex($index)
{
	if (intval($index) < 0)
	{
		throw new MainArgumentNullException('id');
	}

	/** @var CollectableEntity $item */
	foreach ($this->collection as $item)
	{
		if ($item->getInternalIndex() == $index)
		{
			return $item;
		}
	}
	return null;
}