PHP 递归迭代器迭代器:仅获取子目录

我只想使用 RecursiveIteratorIterator 列出主目录中的子目录，

$array_directories = array(
    'core/controller/',
    'core/model/',
    'core/helper/'
);
foreach($array_directories as $path_directory){
   $iterator = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($path_directory),
        RecursiveIteratorIterator::SELF_FIRST
    );
    foreach ($iterator as $fileObject) {
        if ($fileObject->isDir()) {
            $files[] = $fileObject;
        }
    }

}
print_r($files);

结果

Array
(
    [0] => SplFileInfo Object
        (
            [pathName:SplFileInfo:private] => core/controller'webfront
            [fileName:SplFileInfo:private] => webfront
        )
    [1] => SplFileInfo Object
        (
            [pathName:SplFileInfo:private] => core/model'design
            [fileName:SplFileInfo:private] => design
        )
)

但我追求，

Array
(
    [0] => core/controller'webfront
    [1] => core/model'design
)

可能吗？