I am making an iOS project which uses Stripe. I am using a STPCustomerContext and the parameter to create an instance is an object of MainAPI below. When I create the instance, it automatically calls createCustomerKey() but an error (404) is throwing. The URL is "http://localhost:1337/ephemeral_keys" and I believe that is what I have everywhere but yet it is throwing a 404. Here is the code for MainAPI.swift, index.js, & api.js.
The code is:
MainAPI.swift
class MainAPI:NSObject, STPEphemeralKeyProvider {
 //   override init(){}
    static let shared = MainAPI()
    var baseURLString = Constants.BASE_URL
    // MARK: STPEphemeralKeyProvider
    enum CustomerKeyError: Error {
        case missingBaseURL
        case invalidResponse
    }
    func createCustomerKey(withAPIVersion apiVersion: String, completion: @escaping STPJSONResponseCompletionBlock) {
        // the request
        func request(id: String) {
            print("creating a eph key request with customerId: \(id)") // good
            let url = self.baseURLString.appending("/ephemeral_keys")
            Alamofire.request(url, method: .post, parameters: [
                "api_version": apiVersion,
                "customerId": id
                ])
                .validate(statusCode: 200..<300)
                .responseJSON { responseJSON in
                    switch responseJSON.result {
                    case .success(let json):
                        print("created customer ephemeral key!")
                        completion(json as? [String: AnyObject], nil)
                    case .failure(let error):
                        print("could not customer ephemeral key!\n Error info: ")
                        print(error.localizedDescription)
                        completion(nil, error)
                    }
            }
        }
        print("attempting to create customer ephemeral key . . .(createCustomerKey())")
         let customerId = . . . // get customer id
         request(id: costumerId) // this passes on the CORRECT customerId each time
    }
}
api.js
var express = require('express')
var router = express.Router()
var stripe_key = process.env.STRIPE_KEY || "sk_test_myTestKey"
var stripe = require('stripe')(stripe_key);
var request = require("request-promise-native")
//API
router.get('/', function (req, res) {
  res.status(200).send(JSON.stringify({ message: 'API Gateway', success: true, error: null }));
}) // Just for testing, just for error-handling
//1. Create a customer account
router.post('/new_customer', function (req, res) {
  console.log("Creating new customer account...")
  var body = req.body
  stripe.customers.create({ email: body.email, })
    .then((customer) => {
      console.log(customer)
      // Send customerId -> Save this for later use
      res.status(200).send(JSON.stringify({ success: true, error: null, customerId: customer.id }));
    })
    .catch((err) => {  
      console.log(err)
      res.status(400).send(JSON.stringify({ success: false, error: err }))
    });
})
//2. Save Credit Card with token
router.post('/new_card', function (req, res) {
  var customerId = req.body.customerId
  var token = req.body.token
  stripe.customers.update(customerId, { source: token })
    .then((customer) => {
      console.log(customer)
      res.status(200).send(JSON.stringify({ success: true, error: null }));
    })
    .catch((err) => {  
      console.log(err)
      res.status(400).send(JSON.stringify({ success: false, error: err }))
    });
})
//3. Use customerId to post a charge
router.post('/new_charge', function (req, res) {
  var customerId = req.body.customerId
  var amount = req.body.amount
  var source = req.body.source
  stripe.charges.create({
    amount: amount,           //in cents
    currency: "usd",
    customer: customerId,      //CUSTOMER_STRIPE_ACCOUNT_ID
    source: source, // obtained with Stripe.js
  }).then((charge) => {
    res.status(200).send(JSON.stringify({ message: 'Sucess.', success: true, error: null }));
  }).catch((error) =>{
    res.status(400).send(JSON.stringify({ message: 'Error', success: false, error: error }));
  })
})
// here is the error I am assuming
router.post('/ephemeral_keys', (req, res) => {
  const stripe_version = req.body.api_version;
  var customerId = req.body.customerId;
  if (!stripe_version) {
    res.status(400).end();
    return;
  }
  console.log(stripe_version)
  // This function assumes that some previous middleware has determined the
  // correct customerId for the session and saved it on the request object.
  stripe.ephemeralKeys.create(
    {customer: customerId},
    {stripe_version: stripe_version}
  ).then((key) => {
    console.log("Ephemeral key: " + key)
    res.status(200).json(key);
    res.status(200).send(JSON.stringify({ message: 'AAAAhh', success: true, error: null }));
  }).catch((err) => {
    console.log("Ephemeral key error: " + err)
    res.status(200).send(JSON.stringify({ message: 'ABBBBBB', success: true, error: null }));
    res.status(500).end();
  });
});
module.exports = router;
index.js
//Environment Vars
var uri = process.env.NODE_ENV || "development"
console.log(uri + " environment")
//Express App
var express = require('express');
var app = express();
//Api for reading http post request body in express
var bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json())
//Log Connections
app.use(function timeLog (req, res, next) {
  console.log('incoming connection . . . ')
  next()
})
//API middelware
var api = require('./api')
app.use('/api', api)
app.get('/', function (req, res) {
  res.status(200).send(JSON.stringify({ message: 'Welcome!', success: true, error: null }));
}); 
//Create Server
var port = process.env.PORT || 1337;
var httpServer = require('http').createServer(app);
httpServer.listen(port, function () {
  console.log('server running on port ' + port + '.');
});
When I create a STPCustomerContext (like this):
    let apiKeyObject = MainAPI.shared
    customerContext = STPCustomerContext(keyProvider: apiKeyObject)
The following error prints (not allowing the STPPaymentContext later to display):
Response status code was unacceptable: 404.
 
    