KarenK1995

let user = [
    "name": "John",
    "surname": "Smith",
    "age": 18
] as [String : Any]

do {
    let userData = try JSONSerialization.data(withJSONObject: user, options: [])
}
catch {

KarenK1995

let userData = ...
do {
    let json = try? JSONSerialization.jsonObject(with: userData, options: [])
}
catch {
    print(error)
}

KarenK1995

struct User: Codable {
    let name: String
    let surname: String
    let age: Int
}

let user = User(name: "John", surname: "Smith", age: 18)
do {
    let userData = try JSONEncoder().encode(user)
}

KarenK1995

let data = ...
do {
    let user = try JSONDecoder().decode(User.self, from: data)
}
catch {
    print(error)
}