ios - How to convert stored values to JSON format using Swift?

Question

I am trying to convert stored coredata values to JSON format and the JSON format value need to assign a single variable, because this generated JSON I need to send to server. Below code I tried to get coredata stored values but don’t know how to generate JSON required format.

Getting values from coredata

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "User")
    do {
        let results = try context.fetch(fetchRequest)
        let  dateCreated = results as! [Userscore]
            for _datecreated in dateCreated {
                print("(_datecreated.id!)-(_datecreated.name!)") // Output: 79-b 
 80-c 
 78-a
            }
   } catch let err as NSError {
        print(err.debugDescription)
}

Need to Convert Coredata Value to Below JSON format

{
????"status":?true,
????"data":?[
????????{
????????????"id":?"20",
????????????"name":?"a"
????????},
????????{
????????????"id":?"21",
????????????"name":?"b"
????????},
????????{
????????????"id":?"22",
????????????"name":?"c"
????????}
????]
}

Answer 1

Probably the easiest is to convert your object(s) to either dictionaries or arrays (depending on what you need).

First you need to be able to convert your Userscore to dictionary. I will use extension on it since I have no idea what your entity looks like:

extension Userscore {

    func toDictionary() -> [String: Any]? {
        guard let id = id else { return nil }
        guard let name = name else { return nil }
        return [
            "id": id,
            "name": name
        ]
    }

}

Now this method can be used to generate an array of your dictionaries simply using let arrayOfUserscores: [[String: Any]] = userscores.compactMap { $0.toDictionary() }.

Or to build up your whole JSON as posted in question:

func generateUserscoreJSON(userscores: [Userscore]) -> Data? {
    var payload: [String: Any] = [String: Any]()
    payload["status"] = true
    payload["data"] = userscores.compactMap { $0.toDictionary() }
    return try? JSONSerialization.data(withJSONObject: payload, options: .prettyPrinted)
}

This will now create raw data ready to be sent to server for instance

var request = URLRequest(url: myURL)
request.httpBody = generateUserscoreJSON(userscores: userscores)