WordPress: Encurtador de URL usando Bit.ly API e cURL

/*
Encurtador de URL usando a API do Bit.ly e PHP cURL
Como usar: <?php bitly(); ?> ~> coloque no local onde quer que apareça a URL encurtada.
*/

function bitly()
{
    global $post;

    //login information
    $url = get_permalink($post->ID);  //generates wordpress' permalink
    $login = 'YOUR_LOGIN';  //your bit.ly login
    $apikey = 'YOUR_BITLI_API_KEY'; //bit.ly apikey - quintaldosamba
    $format = 'json';   //choose between json or xml
    $version = '2.0.1';

    //create the URL
    $bitly = 'http://api.bit.ly/shorten';
    $param = 'version='.$version.'&longUrl='.urlencode($url).'&login='.$login.'&apiKey='.$apikey.'&format='.$format;

    //get the url
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $bitly . "?" . $param);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $response = curl_exec($ch);
    curl_close($ch);

    //parse depending on desired format
    if(strtolower($format) == 'json')
    {
        $json = @json_decode($response,true);
        echo $json['results'][$url]['shortUrl'];
    }
    else //xml
    {
        $xml = simplexml_load_string($response);
        echo 'http://bit.ly/'.$xml->results->nodeKeyVal->hash;
    }
}