public function getImageUrl($size = 'thumbnail')
    {
        $res = wp_get_attachment_image_src($this->getId(), $size);
        return $res && isset($res[0]) ? $res[0] : null;
    }
public function getImageUrl($size = 'thumbnail')
    {
        $res = wp_get_attachment_image_src($this->getId(), $size);
        return $res && isset($res[0]) ? $res[0] : null;
    }
public function getImageUrl ( $ size = 'thumbnail' ) { $ res = wp_get_attachment_image_src ( $ this -> getId ( ) , $ size ) ; return $ res && isset ( $ res [ 0 ] ) ? $ res [ 0 ] : null ; }
Get attachment image URL.

@param  mixed       $size Arguments accepted by second param of wp_get_attachment_image_src()
@return string|null       Image URL or null if not found
Get attachment image URL .