ACF: Update sort order of repeater fields - functions/php

gistfile1.txt

add_action('wp_ajax_library_set_update_sort', 'library_set_update_sort');
add_action('wp_ajax_nopriv_library_set_update_sort', 'library_set_update_sort');
function library_set_update_sort() {
	$return = array();
	$order = array();

	$new_order = $_POST['new_order'];
	foreach ($new_order as $i => $row) {
		$row = split('-', $row);
		$my_library_id = $row[0];
		$order[] = $row[1];
	}

	$library_expansions = get_field('expansions', 127);
	$sorted_expansions = sortArrayByArray($library_expansions, $order);

	update_field('expansions', $sorted_expansions, 127);
	$return['success'] = "Sort order updated successfully.";

	echo json_encode($return, true);
	die();
}


function sortArrayByArray(Array $array, Array $orderArray) {
    $ordered = array();
    foreach($orderArray as $key) {
        if(array_key_exists($key,$array)) {
            $ordered[$key] = $array[$key];
            unset($array[$key]);
        }
    }
    return $ordered + $array;
}