protected static function cleanDir() {
$flags = \FilesystemIterator::SKIP_DOTS;
$iterator = new \RecursiveDirectoryIterator(self::$tmpDir, $flags);
$iterator = new \RecursiveIteratorIterator($iterator, \RecursiveIteratorIterator::SELF_FIRST);
foreach ($iterator as $file) {
if (is_file($file)) {
unlink($file);
}
}
}