public function OrderItemAccept(array $searchData = Array()) {
        $this->setUrl('https://api.n11.com/ws/OrderService.wsdl');
        self::$_parameters['orderItemList'] = $searchData;
        return self::$_sclient->OrderItemAccept(self::$_parameters);
}

include 'n11.class.php';  

$n11 = new N11($n11Params);

$Onayla = $n11->OrderItemAccept (
[
    "orderItem"=>[
        "id"=> $_GET['id']  
    ]
]                
);
$Onayla->orderItemList->orderItem->productName;

Fatal error: Uncaught SoapFault exception: [Client] SOAP-ERROR: Encoding: object has no 'numberOfPackages' property in C:\xampp\htdocs\entegrev1\fadmin\assets\ajax\n11.class.php:109 Stack trace: #0 C:\xampp\htdocs\entegrev1\fadmin\assets\ajax\n11.class.php(109): SoapClient->__call('OrderItemAccept', Array) #1 C:\xampp\htdocs\entegrev1\fadmin\assets\ajax\siparis-onayla.php(11): N11->OrderItemAccept(Array) #2 {main} thrown in C:\xampp\htdocs\entegrev1\fadmin\assets\ajax\n11.class.php on line 109

$n11Params = ['appKey' => 'API',
              'appSecret' => 'API'];

Class N11 {
    protected static $_appKey, $_appSecret, $_parameters, $_sclient;
    public $_debug = false;
    
    public function __construct(array $attributes = array()) {
        self::$_appKey = $attributes['appKey'];
        self::$_appSecret = $attributes['appSecret'];
        self::$_parameters = ['auth' => ['appKey' => self::$_appKey, 'appSecret' => self::$_appSecret]];
    }
    
    public function setUrl($url) {
        self::$_sclient = new \SoapClient($url);
    }

    public function OrderDetailRequest($searchData) {
        $this->setUrl('https://api.n11.com/ws/OrderService.wsdl');
        self::$_parameters['orderRequest'] = $searchData;
        return self::$_sclient->OrderDetailRequest(self::$_parameters);
    }

    /*HATALI KOD BAŞLANGIÇ*/

    public function OrderItemAccept(array $searchData = Array()) {
        $this->setUrl('https://api.n11.com/ws/OrderService.wsdl');
        self::$_parameters['orderItemList'] = $searchData;
        return self::$_sclient->OrderItemAccept(self::$_parameters);
    }

    /*HATALI KOD BİTİŞ*/

    public function __destruct() {
        if ($this->_debug) {
            print_r(self::$_parameters);
        }
    }
    
}