I want to get values the body in a post using express node.js and an iOS client. Here is my server code:

```
app.post('/user', function (req, res) {
  console.log(req.body)
  console.log(req.body.firstName)
})

```

On the client here is what I'm doing with the json body:

```
let json = ["firstName": "First Dude",
                "lastName": "Last dude"]
    let body = try! JSONSerialization.data(withJSONObject: json, options: [])

```

When I hit the endpoint I get: 

```
{ '{"lastName":"Last dude","firstName":"First Dude"}': '' }
undefined

```

Which looks like the key is the entire json body and the value is empty.

`req.body.firstName` is also undefined.

How can I get a value from a key using body parser?