magento 1.9 how to get the associated products of a configurable sorted by super attribute position?

Question

I need to get all the simple products associated with a configurable, but sorted by the super attribute position, for example, size.

If I have $parent_product, I need $child_s, $child_xl, $child_m, $child_xs sorted by: xs -> position 0, s -> positon 1, m -> position 2, xl -> position 3. So the product order should be $child_xs, $child_s, $child_m, $child_xl

I begin getting all the child product of a configurable this way:

$simpleCollection = Mage::getModel('catalog/product_type_configurable')
                                    ->getUsedProducts(null,$_product);

later I iterate a foreach loop where I use only the products with stock:

foreach ($simpleCollection as $simple):
    if($stockItem->getIsInStock()):
        $label = $simple->getResource()->getAttribute('size')->getFrontend()->getValue($simple);
        echo $label;
    endif;
endforeach;

In the example I print the label of the attibute, but I need and use more data of the products.

The simple products remain unsorted.

I tryed:

usort($simpleCollection, function ($item1, $item2) {
    if ($item1['size'] == $item2['size']) return 0;
    return $item1['size'] < $item2['size'] ? -1 : 1;
});

But it is sorting the products by the size value, that sometimes is the same as product position but not always. So the order I get is not correct, I need the same order in the products than the size position.

Answer 1

Finally I solved it this way:

$attribute = Mage::getSingleton('eav/config')->getAttribute('catalog_product', 'size');
if ($attribute->usesSource()) {
    $sorted_options = $attribute->getSource()->getAllOptions(false);
}

foreach ($sorted_options as $one_option):
    foreach ($simpleCollection as $simple):
        $stockItem = $simple->getStockItem();
        if(!$stockItem->getIsInStock()) { continue; }
        $label = $simple->getResource()->getAttribute('size')->getFrontend()->getValue($simple);
        if ($label != $one_option['label']) { continue; }
        echo $label;
    endforeach;
endforeach;

Doesn't seem very optimized to me, but it works