一旦我在STPAddCardViewController（）上选择完成，应用程序就会加载并且不会停止加载

我使用本教程将付款集成到我的应用中：

https://www.raywenderlich.com/182-accepting-credit-cards-in-your-ios-app-using-stripe#

但是，当我STPAddCardViewController()在应用程序上选择完成时，应用程序将加载并且不会停止加载。我将打印语句添加到本教程中显示的扩展中，希望它可以向我显示代码停滞的位置，但是没有显示任何打印语句。如下所示：

extension OrderDetialsViewController: STPAddCardViewControllerDelegate {

    func addCardViewControllerDidCancel(_ addCardViewController: STPAddCardViewController) {
        print("addCard")
        navigationController?.popViewController(animated: true)
    }

    private func addCardViewController(_ addCardViewController: STPAddCardViewController,
                             didCreateToken token: STPToken,
                             completion: @escaping STPErrorBlock) {
        print("addCard Created Token")
        var totalCost = 0
        for i in 0...localData.shoppingCart.itemSizeArray.count-1{
            if localData.shoppingCart.itemSizeArray[i] == "hd"{
                totalCost = totalCost+2000
            }
            else if localData.shoppingCart.itemSizeArray[i] == "d"{
                totalCost = totalCost+4000
            }
            else if localData.shoppingCart.itemSizeArray[i] == "free"{
                totalCost = totalCost + 0
            }
            else if localData.shoppingCart.itemSizeArray[i] == "home" {
                totalCost = totalCost + 500
            }
        }
        StripeClient.shared.completeCharge(with: token, amount: totalCost) { result in
            print("StripeClient")
          switch result {
          case .success:
            completion(nil)
            let alertController = UIAlertController(title: "Congrats on your order",
                                  message: "Your payment was successful! Check email for confirmation!",
                                  preferredStyle: .alert)
            let alertAction = UIAlertAction(title: "OK", style: .default, handler: { _ in
              self.navigationController?.popViewController(animated: true)
            })
            alertController.addAction(alertAction)
            self.present(alertController, animated: true)
            self.createOrderEmailBody()
            self.createCustomerOrderBody()
            self.changeUserRewardsScore()
          case .failure(let error):
            print(error)
            completion(error)
          }
        }
  }
}