Получить одно значение из массива объектов PHP

Я очень новичок в PHP, и я хочу получить одно значение из объекта OpenGraph и распечатать его. Не уверен, что я делаю не так? Я продолжаю получать «Массив» как распечатку.

class OpenGraph implements Iterator{

public static $TYPES = array(
'activity' => array('activity', 'sport'),
'business' => array('bar', 'company', 'cafe', 'hotel', 'restaurant'),
'group' => array('cause', 'sports_league', 'sports_team'),
'organization' => array('band', 'government', 'non_profit', 'school', 'university'),
'person' => array('actor', 'athlete', 'author', 'director', 'musician', 'politician', 'public_figure'),
'place' => array('city', 'country', 'landmark', 'state_province'),
'product' => array('album', 'book', 'drink', 'food', 'game', 'movie', 'product', 'song', 'tv_show'),
'website' => array('blog', 'website'),
);

private $_values = array();

static public function fetch($URI) {
$curl = curl_init($URI);
curl_setopt($curl, CURLOPT_FAILONERROR, true);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_TIMEOUT, 15);
curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
$response = curl_exec($curl);
curl_close($curl);
if (!empty($response)) {
return self::_parse($response);
} else {
return false;
}
}

static private function _parse($HTML) {
$old_libxml_error = libxml_use_internal_errors(true);
$doc = new DOMDocument();
$doc->loadHTML($HTML);

libxml_use_internal_errors($old_libxml_error);
$tags = $doc->getElementsByTagName('meta');
if (!$tags || $tags->length === 0) {
return false;
}
$page = new self();
$nonOgDescription = null;

foreach ($tags AS $tag) {
if ($tag->hasAttribute('property') &&
strpos($tag->getAttribute('property'), 'og:') === 0) {
$key = strtr(substr($tag->getAttribute('property'), 3), '-', '_');
$page->_values[$key] = $tag->getAttribute('content');
}

//Added this if loop to retrieve description values from sites like the New York Times who have malformed it.
if ($tag ->hasAttribute('value') && $tag->hasAttribute('property') &&
strpos($tag->getAttribute('property'), 'og:') === 0) {
$key = strtr(substr($tag->getAttribute('property'), 3), '-', '_');
$page->_values[$key] = $tag->getAttribute('value');
}
//Based on modifications at https://github.com/bashofmann/opengraph/blob/master/src/OpenGraph/OpenGraph.php
if ($tag->hasAttribute('name') && $tag->getAttribute('name') === 'description') {
$nonOgDescription = $tag->getAttribute('content');
}

}
//Based on modifications at https://github.com/bashofmann/opengraph/blob/master/src/OpenGraph/OpenGraph.php
if (!isset($page->_values['title'])) {
$titles = $doc->getElementsByTagName('title');
if ($titles->length > 0) {
$page->_values['title'] = $titles->item(0)->textContent;
}
}
if (!isset($page->_values['description']) && $nonOgDescription) {
$page->_values['description'] = $nonOgDescription;
}
//Fallback to use image_src if ogp::image isn't set.
if (!isset($page->values['image'])) {
$domxpath = new DOMXPath($doc);
$elements = $domxpath->query("//link[@rel='image_src']");
if ($elements->length > 0) {
$domattr = $elements->item(0)->attributes->getNamedItem('href');
if ($domattr) {
$page->_values['image'] = $domattr->value;
$page->_values['image_src'] = $domattr->value;
}
}
}
if (empty($page->_values)) { return false; }

return $page;
}

public function __get($key) {
if (array_key_exists($key, $this->_values)) {
return $this->_values[$key];
}

if ($key === 'schema') {
foreach (self::$TYPES AS $schema => $types) {
if (array_search($this->_values['type'], $types)) {
return $schema;
}
}
}
}

public function keys() {
return array_keys($this->_values);
}

public function __isset($key) {
return array_key_exists($key, $this->_values);
}

public function hasLocation() {
if (array_key_exists('latitude', $this->_values) && array_key_exists('longitude', $this->_values)) {
return true;
}

$address_keys = array('street_address', 'locality', 'region', 'postal_code', 'country_name');
$valid_address = true;
foreach ($address_keys AS $key) {
$valid_address = ($valid_address && array_key_exists($key, $this->_values));
}
return $valid_address;
}

private $_position = 0;
public function rewind() { reset($this->_values); $this->_position = 0; }
public function current() { return current($this->_values); }
public function key() { return key($this->_values); }
public function next() { next($this->_values); ++$this->_position; }
public function valid() { return $this->_position < sizeof($this->_values); }}

Реализация:

require_once('OpenGraph.php');
$graph = OpenGraph::fetch('http://www.google.com');
echo $graph->keys('description');

Я на самом деле получил этот код из GitHub здесь: https://github.com/scottmac/opengraph