将来の支払いを設定する

import UIKit
import StripePaymentSheet

class CheckoutViewController: UIViewController {
  @IBOutlet weak var checkoutButton: UIButton!
  var paymentSheet: PaymentSheet?
  let backendCheckoutUrl = URL(string: "Your backend endpoint/payment-sheet")! // Your backend endpoint

  override func viewDidLoad() {
    super.viewDidLoad()

    checkoutButton.addTarget(self, action: #selector(didTapCheckoutButton), for: .touchUpInside)
    checkoutButton.isEnabled = false

    // MARK: Fetch the SetupIntent client secret, Ephemeral Key secret, Customer ID, and publishable key
    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 setupIntentClientSecret = json["setupIntent"] as? String,
            let publishableKey = json["publishableKey"] as? String,
            let self = self else {
        // Handle error
        return
      }

      STPAPIClient.shared.publishableKey = publishableKey
      // MARK: Create a PaymentSheet instance
      var configuration = PaymentSheet.Configuration()
      configuration.merchantDisplayName = "Example, Inc."
      configuration.customer = .init(id: customerId, ephemeralKeySecret: customerEphemeralKeySecret)
      // Set `allowsDelayedPaymentMethods` to true if your business handles
      // delayed notification payment methods like US bank accounts.
      configuration.allowsDelayedPaymentMethods = true
      self.paymentSheet = PaymentSheet(setupIntentClientSecret: setupIntentClientSecret, configuration: configuration)

      DispatchQueue.main.async {
        self.checkoutButton.isEnabled = true
      }
    })
    task.resume()
  }

}

@objc
func didTapCheckoutButton() {
  // MARK: Start the checkout process
  paymentSheet?.present(from: self) { paymentResult in
    // MARK: Handle the payment result
    switch paymentResult {
    case .completed:
      print("Your order is confirmed")
    case .canceled:
      print("Canceled!")
    case .failed(let error):
      print("Payment failed: \(error)")
    }
  }
}