Ios Shopify与客户同步购物车

在成功登录后的上述代码中，我尝试为用户创建购物车。然后我将项目添加到购物车，但当我关闭并重新打开应用程序时，购物车是空的

如何为用户创建购物车，以便他们能够在任何设备上访问购物车

[self.client loginCustomerWithCredentials:credentials callback:^(BUYCustomer * customer, BUYCustomerToken * token, NSError * _Nullable error) {
            if (customer && !error) {
                self.appDelegate.cart = [self.client.modelManager insertCartWithJSONDictionary:nil];
                NSLog(@"Success fully loged in token %@ %@",token.accessToken,token.customerID);
                UINavigationController *navigationController = self.navigationController;
                [navigationController popViewControllerAnimated:YES];

            }else{
                [self showEror:@"LogIn Failed" message:@"Please provide valid Details"];
            }
        }];