gistfile1.php

<?php

class MyRecursiveFilterIterator extends RecursiveFilterIterator {
    public function accept() {
        return 
          $this->current()->isDir() && 
          strpos($this->current()->getFilename(), '.') === false;
    }
}

$dirItr    = new RecursiveDirectoryIterator('/Users/gdunne/Downloads/', RecursiveDirectoryIterator::SKIP_DOTS);
$filterItr = new MyRecursiveFilterIterator($dirItr);
$itr       = new RecursiveIteratorIterator($filterItr, RecursiveIteratorIterator::SELF_FIRST);

foreach ($itr as $filePath => $fileInfo) {
    echo $fileInfo . PHP_EOL;
}