Stripe.swift

// PaymentViewController.swift
class PaymentViewController: UIViewController, STPPaymentCardTextFieldDelegate {
  let paymentTextField = STPPaymentCardTextField()
    
  // Next, let's instantiate the STPPaymentCardTextField, set the PaymentViewController as its STPPaymentCardTextFieldDelegate, and add it to our view.
  override func viewDidLoad() {
    super.viewDidLoad();
    paymentTextField.frame = CGRectMake(15, 15, CGRectGetWidth(self.view.frame) - 30, 44)
    paymentTextField.delegate = self
    view.addSubview(paymentTextField)
    // This will add an STPPaymentCardTextField to the controller to accept card numbers, expiration dates, and CVCs. It'll format the input, and validate it on the fly.
  }
  
  // When the user enters text into this field, the paymentCardTextFieldDidChange: method will be called on our view controller. In this callback, we can enable a save button that allows users to submit their valid cards if the form is valid:
  func paymentCardTextFieldDidChange(textField: STPPaymentCardTextField) {
    // Toggle navigation, for example
    saveButton.enabled = textField.isValid
  }
  
  // Once you've collected the card number, expiration, and CVC, package them up in an STPCardParams object and invoke the createTokenWithCard: method on the STPAPIClient class, instructing the library to send off the credit card data to Stripe and return a token.
  @IBAction func save(sender: UIButton) {
    if let card = paymentTextField.card {
        STPAPIClient.sharedClient().createTokenWithCard(card) { (token, error) -> Void in
            if let error = error  {
                handleError(error)
            }
            else if let token = token {
                createBackendChargeWithToken(token) { status in
                    ...
                }
            }
        }
    }
  }
  
  // Sending the token to your server
  func createBackendChargeWithToken(token: STPToken, completion: STPPaymentAuthorizationStatus -> ()) {
    let url = NSURL(string: "https://example.com/token")!
    let request = NSMutableURLRequest(URL: url)
    request.HTTPMethod = "POST"
    let body = "stripeToken=(token.tokenId)"
    request.HTTPBody = body.dataUsingEncoding(NSUTF8StringEncoding)
    let configuration = NSURLSessionConfiguration.ephemeralSessionConfiguration()
    let session = NSURLSession(configuration: configuration)
    let task = session.dataTaskWithRequest(request) { (data, response, error) -> Void in
        if error != nil {
            completion(STPPaymentAuthorizationStatus.Failure)
        }
        else {
            completion(STPPaymentAuthorizationStatus.Success)
        }
    }
    task.resume()
  }
}