func showDropIn(clientTokenOrTokenizationKey: String) {
    let request =  BTDropInRequest()
    let dropIn = BTDropInController(authorization: clientTokenOrTokenizationKey, request: request)
    { (controller, result, error) in
        if (error != nil) {
            print("ERROR")
        } else if (result?.isCanceled == true) {
            print("CANCELED")
        } else if let result = result {
            // Use the BTDropInResult properties to update your UI
            let selectedPaymentMethodType = result.paymentMethodType
            let selectedPaymentMethod = result.paymentMethod
            let selectedPaymentMethodIcon = result.paymentIcon
            let selectedPaymentMethodDescription = result.paymentDescription
        }
        controller.dismiss(animated: true, completion: nil)
    }
    self.present(dropIn!, animated: true, completion: nil)
}

let request = BTDropInRequest()

let threeDSecureRequest = BTThreeDSecureRequest()
threeDSecureRequest.threeDSecureRequestDelegate = self

threeDSecureRequest.amount = 1.00
threeDSecureRequest.email = "[email protected]"
threeDSecureRequest.requested = .version2

let address = BTThreeDSecurePostalAddress()
address.givenName = "Jill"
address.surname = "Doe"
address.phoneNumber = "5551234567"
address.streetAddress = "555 Smith St"
address.extendedAddress = "#2"
address.locality = "Chicago"
address.region = "IL"
address.postalCode = "12345"
address.countryCodeAlpha2 = "US"
threeDSecureRequest.billingAddress = address

// Optional additional information.
// For best results, provide as many of these elements as possible.
let additionalInformation = BTThreeDSecureAdditionalInformation()
additionalInformation.shippingAddress = address
threeDSecureRequest.additionalInformation = additionalInformation

request.threeDSecureRequest = threeDSecureRequest

let request =  BTDropInRequest()
request.vaultManager = true

BTDropInResult.mostRecentPaymentMethod(forClientToken: authorization) { result, error in
  guard let result = result, error == nil else {
    // either an error occurred or the customer doesn't have any vaulted payment methods
    return
  }

  if result.paymentOptionType == .applePay {
    // Apple Pay is the most recently selected option
    // Note that result.paymentMethod will be nil in this case; display Apple Pay button and tokenize using `BTApplePayClient`
  }

  // Update your UI
  let type = result.paymentMethodType
  let icon = result.paymentIcon
  let description = result.paymentDescription

  // Use the payment method to transact
  let paymentMethod = result.paymentMethod
}

let uiCustomization = BTDropInUICustomization(colorScheme: .dark)

let dropInRequest = BTDropInRequest()
dropInRequest.uiCustomization = uiCustomization

let uiCustomization = BTDropInUICustomization(colorScheme: .dynamic)
uiCustomization.fontFamily = "Helvetica"
uiCustomization.boldFontFamily = "Helvetica Bold"

let dropInRequest = BTDropInRequest()
dropInRequest.uiCustomization = uiCustomization

let uiCustomization = BTDropInUICustomization(colorScheme: .light)
uiCustomization.disableDynamicType = true

let dropInRequest = BTDropInRequest()
dropInRequest.uiCustomization = uiCustomization