我正在使用本教程通过firebase将我的应用程序与stripe连接-
https://stripe.com/docs/payments/accept-a-payment?platform=ios&ui=payment-sheet&uikit-swiftui=swiftui
我找不到paymentsheet。为什么它这么说，如何排序出来？我只是想连接条纹到我的应用程序使用firebase。什么是paymentsheet。我必须写某种形式的工作表？什么应该是其他代码与之相关？我已经附上了截图的错误，以及写在它的粗体字。
下面是错误的屏幕截图：-

现在，我的视图控制器是：

import Stripe
   import SwiftUI

   class MyBackendModel: ObservableObject {
 let backendCheckoutUrl = URL(string: "Your backend endpoint")! // Your backend endpoint
 @Published var paymentSheet: PaymentSheet?//**Cannot find type 'PaymentSheet' in scope**
 @Published var paymentResult: PaymentSheetResult?//**Cannot find type 'PaymentSheet' in scope**

   init() {
   STPAPIClient.shared.publishableKey = 

"pk_test_51HmAsMFzRM1fSBZ2tTT1SxPxRBzParFfjm6s0aXD0F5dYLeOSVCKtiZ4lq0TGwJxPhHpsq6Hga7I0QzRWisPYMdj00bDxAMTKf"

 }

    func preparePaymentSheet() {
  // MARK: Fetch the PaymentIntent and Customer information from the backend
   var request = URLRequest(url: backendCheckoutUrl)
   request.httpMethod = "POST"
    let task = URLSession.shared.dataTask(with: request, completionHandler: { [weak self] (data, response, error) in
  guard let data = data,
        let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String : Any],
        let customerId = json["customer"] as? String,
        let customerEphemeralKeySecret = json["ephemeralKey"] as? String,
        let paymentIntentClientSecret = json["paymentIntent"] as? String,
        let self = self else {
        // Handle error
        return
      }

  // MARK: Create a PaymentSheet instance
  var configuration = PaymentSheet.Configuration()
  configuration.merchantDisplayName = "Example, Inc."
  configuration.customer = .init(id: customerId, ephemeralKeySecret: customerEphemeralKeySecret)

  DispatchQueue.main.async {
    self.paymentSheet = PaymentSheet(paymentIntentClientSecret: paymentIntentClientSecret, configuration: configuration)
    }
    })
    task.resume()
  }

     func onPaymentCompletion(result: PaymentSheetResult) {
    self.paymentResult = result
   }
  }

 struct CheckoutView: View {
  @ObservedObject var model = MyBackendModel()

   var body: some View {
    VStack {
    if let paymentSheet = model.paymentSheet {
    PaymentSheet.PaymentButton(
      paymentSheet: paymentSheet,
      onCompletion: model.onPaymentCompletion
        ) {
        Text("Buy")
        }
        } else {
        Text("Loading…")
       }
      if let result = model.paymentResult {
       switch result {
      case .completed:
        Text("Payment complete")
       case .failed(let error):
        Text("Payment failed: \(error.localizedDescription)")
       case .canceled:
      Text("Payment canceled.")
      }
      }
      }.onAppear { model.preparePaymentSheet() }
     }
    }

请协助我。我一直在尝试这么长时间来连接我的应用程序到条纹，但不成功。我只是想我的客户ID。显示条纹 Jmeter 板和其他信息也。