include 'vendor/autoload.php';

$filename = '/path/to/file/file.xml';

//   XMLReader driver - for medium and large xml files
//   SimpleXML driver - for small xml files

$parser = new \YMLParser\YMLParser(new \YMLParser\Driver\XMLReader);
$parser->open($filename); // throws \Exception if $filename doesn't exist or empty
foreach($parser->getOffers() as $offer): // YMLParser::getOffers() returns \Generator
    echo $offer['url'];
endforeach;

include 'vendor/autoload.php';

$filename = '/path/to/file/file.xml';

$parser = new \YMLParser\YMLParser(new \YMLParser\Driver\SimpleXML);
$parser->open($filename);

// We want offers only with not empty url subelements
$filter = function($element) { return !empty($element['url']); }; 
$offers = iterator_to_array($parser->getOffers($filter));

// Let's get all params from first offer if they are exist
foreach($offers[0]['params'] as $param):
	echo $param['name'] . ' - ' . $param['value'];
endforeach;