Converting inherited class to JSON in Swift 4.2 - swift

Question

I'm new to Swift, I'm trying to have this JSON
{
"title": "newSurvey",
"pages": [
{
"questions": [
{
"title": "Untitled Question",
"type": "QUESTION_SLIDER",
"content": {
"min": "1",
"max": "10",
"step": "3",
"defaultValue": "5"
}
},
{
"title": "asdasddfdf",
"type": "QUESTION_TEXT",
"choices": ["choice1","choice2"]
}
]
}
]}
I'm suffering from converting subclass to JSON
I thought about divide my code to three objects then add them to the final
string from jsonEncoder
so that's what I did
public class Question : Encodable {
var title : String?
var description: String?
init(_ title: String , _ desc: String) {
self.title = title
self.description = desc
}}
struct Questions : Encodable{
var questions : [Question]
}
class Create : Encodable {
var title : String?
var pages : [Questions] = []
init(_ title:String , _ q : Questions) {
self.title = title
self.pages.append(q)
}
func postData () -> String{
let jsonEncoder = JSONEncoder()
do {
jsonEncoder.outputFormatting = .prettyPrinted
let jsonData = try jsonEncoder.encode([self])
let json = String(data: jsonData ,encoding: .utf8)
print( json!)
return json!
}
catch {
print("Error")
}
return ""
}
class Content :Encodable {
init(_ min : Int , _ max : Int){
self.min = min
self.max = max
}
var min : Int?
var max : Int?
var minLabel : String?
var maxLabel : String?
var defaultValue : Int?
var step : Int?
}
class SliderQuestion :Question {
let TYPE = "SHORT TEXT"
var content = Content(0,2)
init(_ title: String, _ desc: String,_ content : Content ) {
self.content = content
super.init(title, desc)
}
}
I'm sorry for the long code but I want to clarify my idea, is there any way to have the subclass converted to JSON?