PKPaymentAuthVC

    func paymentAuthorizationViewController(_ controller: PKPaymentAuthorizationViewController, didAuthorizePayment payment: PKPayment, completion: @escaping (PKPaymentAuthorizationStatus) -> Void) {

        STPAPIClient.shared().createToken(with: payment) { (token: STPToken?, error: Error?) in
            guard let token = token, error == nil else {
                completion(.failure)
                return
            }

            API_Client.sharedInstance.attachToCustomerAndCharge(tokenId: token.stripeID) { (error) in
                if error != nil {
                    // Notify payment authorization view controller
                    completion(.failure)
                }
                else {
                    // Notify payment authorization view controller
                    completion(.success)
                }
            }
        }
    }