sample of a CategoryIterator for categoryTree from news

CategoryIterator.php

<?php

namespace Datenbetrieb\D4b6NewsNotification\Utility;

/**
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

/**
 * Simple Iterator for CategoryTree from news categoryRepository
 *
 * example for usage:
 *
 * $iterator = new \RecursiveIteratorIterator(new CategoryIterator($categoryTree), \RecursiveIteratorIterator::SELF_FIRST);
 * foreach($iterator as $key => $value) {
 *     $categoryId = $value['item']->getUid();
 * }
 */
class CategoryIterator extends \ArrayIterator implements \RecursiveIterator
{
    public function __construct (array &$data)
    {
        parent::__construct($data);
    }

    public function hasChildren()
    {
        $current = $this->current();
        return (isset($current['children']) && count($current['children']) > 0);
    }

    public function getChildren()
    {
        $current = $this->current();
        return new self($current['children']);
    }
}