Swift: send POST request with JSONEncoder encoded data does not work - json

Question

I am using the JSONEncoder that has been provided with Swift4.
I have a class called Customer that uses the Codable protocol. Inside of Customer there are four Strings.
class Customer: Codable {
var title: String
var firstName: String
var lastName: String
var email: String
}
Reading JSON with a GET Request works fine.
URLSession.shared.dataTask(with: url) { (data, response, error) in
if error != nil {
print(error!.localizedDescription)
}
guard let data = data else { return }
do {
let customer = try JSONDecoder().decode(Customer.self, from: data)
DispatchQueue.main.async {
print("\(customer.title)")
print("\(customer.firstName)")
print("\(customer.lastName)")
print("\(customer.email)")
}
} catch let jsonError {
print(jsonError)
}
}.resume()
However when I start to do a POST request I am lost:
First set up the request object:
let urlString = "http://localhost:8000/customer"
guard let url = URL(string: urlString) else { return }
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.setValue("Application/json", forHTTPHeaderField: "Content-Type")
let customer = Customer()
customer.title = "Mr"
customer.firstName = "Chuck"
customer.lastName = "Norris"
customer.email = "chuck.norris#awsome.com"
let encodedData = try? JSONEncoder().encode(customer)
print(String(data: encodedData!, encoding: .utf8)!) //<- Looks as intended
// Output is {"firstName":"Chuck","lastName":"Norris","title":"MR","email":"chuck.norris#awesome.com "}
Now send it out
request.httpBody = encodedData //
URLSession.shared.dataTask(with: request, completionHandler: {(data, response, error) in
if let response = response {
print(response)
}
if let data = data {
do {
let json = try JSONSerialization.data(withJSONObject: data, options: [])
print(json)
}catch {
print(error)
}
}
})
In return I receive the message "The given data was not valid JSON."
So, my assumption is that I simply can not just put the encoded JSON data into the http body of my request.
Browsing through some articles about URLSession and JSON I found that it seems that I need to serialize my encoded JSON:
var json: Any?
if let data = encodedData {
json = try? JSONSerialization.jsonObject(with: data, options: .allowFragments)
}
Now, I don't know how to proceed. First I do not understand why I should serialize my JSON to something that can not simply put into a httpBody.
Because JSONSerialization.jsonObject produces Any? and not Data.
Update
Now, I was able to successfully send my data to my server. I am still trying to understand what was wrong - because I did not changed anything (except for the removal of the JSONSerialization call inside the completion Handler. I will investigate further...
...And .resume had been missing. :-)