ApplePaybutton无法正常运行（ApplePay与Stripe集成）

Question

我正在尝试使用Stripe集成Applepay，以便用户能够轻松付款。我使用heroku帐户作为后端服务器。我可以在用户界面上添加ApplePay按钮（请查看我当前的故事板）并尝试配置一个来自底部的弹出结账窗口供用户付款。 My Current UI 但是，即使我点击ApplePaybutton，也没有任何反应。我的目标是在用户点击ApplePay按钮My Goal UI时创建结帐窗口。 我假设按下按钮时应调用func beginPayment()但不起作用。我怀疑if (stripePublishableKey == "") {和之后的代码设置不正确。任何帮助，将不胜感激！

import UIKit
import Stripe

enum STPBackendChargeResult {
case success, failure
}

typealias STPTokenSubmissionHandler = (STPBackendChargeResult?, NSError?) -> Void


class ViewController: UIViewController, PKPaymentAuthorizationViewControllerDelegate {

let stripePublishableKey = "my Stripe PublishableKey"

let backendChargeURLString = "my heroku URL"

let appleMerchantId = "my apple merchand Id"

let shirtPrice : UInt = 1000 // this is in cents

override func viewDidLoad() {
    super.viewDidLoad()

    //This is the method of making the ApplePayButton( didn't use storyboard)
    let button = PKPaymentButton(type: .buy, style: .black)
    button.addTarget(self, action: #selector(ViewController.beginPayment(_:)), for: .touchUpInside)
    let bw = button.frame.size.width
    let bh = button.frame.size.height
    let vw = view.frame.size.width
    let vh = view.frame.size.height
    button.frame = CGRect(origin: CGPoint(x: vw/2 - bw/2, y: vh/2 - bh/2), size: button.frame.size)

    view.addSubview(button)

}
//This func is supposed to be called when ApplePayButton is pressed.
func beginPayment(_: UIButton) {

    if (stripePublishableKey == "") {

        let alert = UIAlertController(
            title: "You need to set your Stripe publishable key.",
            message: "You can find your publishable key at https://dashboard.stripe.com/account/apikeys .",
            preferredStyle: UIAlertControllerStyle.alert
        )
        let action = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil)
        alert.addAction(action)
        present(alert, animated: true, completion: nil)


        return


    }

    if (appleMerchantId != "") {

         let paymentRequest = Stripe.paymentRequest(withMerchantIdentifier: appleMerchantId) 

            if Stripe.canSubmitPaymentRequest(paymentRequest) {

                paymentRequest.paymentSummaryItems = [PKPaymentSummaryItem(label: "Cool shirt", amount: NSDecimalNumber(string: "10.00")), PKPaymentSummaryItem(label: "Stripe shirt shop", amount: NSDecimalNumber(string: "10.00"))]
                let paymentAuthVC = PKPaymentAuthorizationViewController(paymentRequest: paymentRequest)
                paymentAuthVC.delegate = self
                self.present(paymentAuthVC, animated: true, completion: nil)

                return  

        }

    } else {

        print("You should set an appleMerchantId.")
    }
}

func paymentAuthorizationViewController(_ controller: PKPaymentAuthorizationViewController, didAuthorizePayment payment: PKPayment, completion: @escaping ((PKPaymentAuthorizationStatus) -> Void)) {
    let apiClient = STPAPIClient(publishableKey: stripePublishableKey)
    apiClient.createToken(with: payment, completion: { (token, error) -> Void in
        if error == nil {

            if let token = token {
                self.createBackendChargeWithToken(token, completion: { (result, error) -> Void in
                    if result == STPBackendChargeResult.success {
                        completion(PKPaymentAuthorizationStatus.success)
                    }
                    else {
                        completion(PKPaymentAuthorizationStatus.failure)
                    }
                })
            }
        }
        else {
            completion(PKPaymentAuthorizationStatus.failure)
        }
    })
}

func paymentAuthorizationViewControllerDidFinish(_ controller: PKPaymentAuthorizationViewController) {
    dismiss(animated: true, completion: nil)
}

func createBackendChargeWithToken(_ token: STPToken, completion: @escaping STPTokenSubmissionHandler) {
    if backendChargeURLString != "" {
        if let url = URL(string: backendChargeURLString  + "/charge") {

            let session = URLSession(configuration: URLSessionConfiguration.default)
            let request = NSMutableURLRequest(url: url)
            request.httpMethod = "POST"
            let postBody = "stripeToken=\(token.tokenId)&amount=\(shirtPrice)"
            let postData = postBody.data(using: String.Encoding.utf8, allowLossyConversion: false)
            session.uploadTask(with: request as URLRequest, from: postData, completionHandler: { data, response, error in
                let successfulResponse = (response as? HTTPURLResponse)?.statusCode == 200
                if successfulResponse && error == nil {
                    completion(.success, nil)
                } else {
                    if error != nil {
                        completion(.failure, error as NSError?)
                    } else {
                        completion(.failure, NSError(domain: StripeDomain, code: 50, userInfo: [NSLocalizedDescriptionKey: "There was an error communicating with your payment backend."]))
                    }

                }
            }).resume()

            return
        }
    }
    completion(STPBackendChargeResult.failure, NSError(domain: StripeDomain, code: 50, userInfo: [NSLocalizedDescriptionKey: "You created a token! Its value is \(token.tokenId). Now configure your backend to accept this token and complete a charge."]))
}
}