Sorting finder results - directory first.

sorting-finder.php

<?php

Finder::extensionMethod('sort', function (Finder $finder, $callback) {
    $result = iterator_to_array($finder);
    uasort($result, $callback);
    return new \ArrayIterator($result);
});

$index = Finder::find('*')->in($dir)->sort(function (\SplFileInfo $a, \SplFileInfo $b) {
    return $a->isDir() ? ($b->isDir() ? strnatcasecmp($a->getBasename(), $b->getBasename()) : -1)
        : ($b->isDir() ? 1 : (
            strcasecmp($a->getExtension(), $b->getExtension()) == 0
                ? strnatcasecmp($a->getBasename(), $b->getBasename()) : strcasecmp($a->getExtension(), $b->getExtension())
        ));
});