void Start()
    {
        if (!CoreXT.IsDevice)
        {
            Debug.Log("StoreProductViewController is only available on the device.");
            return;
        }

        _productViewControllerDelegate  = new StoreProductViewControllerDelegate();
        _productViewController          = new SKStoreProductViewController();
        _productViewController.Delegate = _productViewControllerDelegate;

        LoadProduct(ItemIdentifier);
    }
    void Start()
    {
        if ( !CoreXT.IsDevice )
        {
            Debug.Log ("StoreProductViewController is only available on the device.");
            return;
        }

        _productViewControllerDelegate = new StoreProductViewControllerDelegate();
        _productViewController = new SKStoreProductViewController();
        _productViewController.Delegate = _productViewControllerDelegate;

        LoadProduct(ItemIdentifier);
    }