Issue with Codable object to JSON conversion - json

Question

Apologies if this is a basic question, I am new using Apis and JSON in Swift. I am attempting to submit a post request but am receiving:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (__SwiftValue)'.
I believe that this is due to a incorrect/unconvertible type but I have tried multiple different permutations of the variables I am passing and it continues to fail.
Here is my ContentView:
struct ContentView: View {
#State var town: Space = Space(title: "test city", description: "is this working")
var body: some View {
Button(action: {
Api.postRequest(param: ["space" : town], urlString: Api.spacePostUrl) { (update) in
print("\(update)")
}
}) {
Text("Post Request")
}
}
}
The underlying data struct:
struct Space: Codable {
var title: String
var description: String
}
And my attempted API call:
class Api {
static let spacePostUrl = "http://localhost:3001/spaces"
static let spaceGetUrl = "http://localhost:3001/"
static func postRequest(param: [String : Codable], urlString: String, completion: #escaping (Int) -> ()) {
guard let url = URL(string: urlString) else { return }
let body = try? JSONSerialization.data(withJSONObject: param)
var request = URLRequest(url: url)
request.httpBody = body
request.httpMethod = "POST"
URLSession.shared.dataTask(with: request) { (data, request, error) in
guard let update = data else { return }
do {
let update = try JSONDecoder().decode(Int.self, from: update)
DispatchQueue.main.async {
completion(update)
}
}
catch {
print(error)
}
}
}
}

Answer 1

class Api {
static let spacePostUrl = "http://localhost:3001/spaces"
static let spaceGetUrl = "http://localhost:3001/"
static func postRequest(param: [String : Codable], urlString: String, completion: #escaping (Int) -> ()) {
guard let url = URL(string: urlString) else { return }
let body = try? JSONSerialization.data(withJSONObject: param)
var request = URLRequest(url: url)
request.httpBody = body
request.httpMethod = "POST"
let task = URLSession.shared.dataTask(with: request) { (data, request, error) in
guard let update = data else { return }
do {
let update = try JSONDecoder().decode(Space.self, from: update)
DispatchQueue.main.async {
completion(update)
}
}
catch {
print(error)
}
}
task.resume()
}
}