Get Wordpress Feeds cache supports

<?php

Class RssReader {

    public $feedUrl; // Feed URL

    public $cache = true; // enable cache

    public $cacheTime = 86400; // 1 day


    public function __construct($feedUrl) {


        $this->feedUrl = $feedUrl;

    }

    protected function _getFeedSource() {

        if($this->cache) {
            if(!file_exists('feed.xml')) {
                $this->_downloadFeed();
            } else if(file_exists('feed.xml') && filemtime('feed.xml') <= time() - $this->cacheTime) {
                $this->_downloadFeed();
            }
        } else {
            $this->_downloadFeed();
        }


        return 'feed.xml';

    }

    protected function _downloadFeed() {

        $xml = file_get_contents($this->feedUrl);
        file_put_contents('feed.xml', $xml);

    }

    public function getRssItems() {

        $source = $this->_getFeedSource();

        $content = file_get_contents($source);
        $feed = new SimpleXmlElement($content);

        return $feed->channel->item ;

    }

}

$reader = new RssReader('https://en.blog.wordpress.com/feed/');
?>
<div>
<?php foreach($reader->getRssItems() as $item):?>
    <div>
        <?=$item->title;?><br>
        Kategóriák:
        <?php foreach($item->category as $category):?>
            <?=$category;?>
        <?php endforeach;?>
        <br>
        Kép:
        <img src="<?=$item->children('media', true)->thumbnail->attributes();?>" width="150">
        <br>
        <?=$item->link;?><br>
        <?=$item->description;?><br>
    </div>
    <hr>
<?php endforeach;?>
</div>