php arbitary sort

<?php
function customSort($a, $b) {
    $arrOrder = [4, 1, 3, 2];
    $aIx = array_search($a[0], $arrOrder);
    $bIx = array_search($b[0], $arrOrder);

    if ($aIx === false)
        return 1;
    elseif ($bIx === false)
        return -1;
    else
        return ($aIx < $bIx)?-1:1;
}

$arrItems = [
        [1, 'First Item'],
        [4, 'Fourth Item'],
        [2, 'Second Item'],
        [3, 'Third Item'],
];

usort($arrItems, 'customSort');

var_dump($arrItems);