JsonEncoder always return empty array

Question

Im trying to save struct array into UserDefaults and I cant figure out why JsonEncoder return empty data. I have setup model that conforms Codable protocol

struct MenuItem : Codable{
    let name : String?
    let icon : String?

    init(name : String?, icon : String?){
        self.name = name
        self.icon = icon
    }
}

and also created Defaults manager for saving it into user defaults.

class DefaultsManager {

    static let shared = DefaultsManager()

    init(){}

    var items: [MenuItem]{
        get{
            if let json = UserDefaults.standard.data(forKey: "key"){
                return decodeFromJson(jsonData: json)
            } else {
                return []
            }
        }
        set{
            let json = codeToJson(data: items)
            UserDefaults.standard.set(json, forKey: "key")
        }
    }

    fileprivate func codeToJson<T:Codable>(data: Array<T>) -> Data?{
        do {
            return try JSONEncoder().encode(data)
        } catch {
            print(error)
            return nil
        }
    }

    fileprivate func decodeFromJson<T:Codable>(jsonData: Data) -> [T]{
        do {
            return try JSONDecoder().decode(Array<T>.self, from: jsonData)
        } catch {
            print(error)
            return []
        }
    }
}

but whatever I do JsonEncoder returns empty data.. I tried to google but without success.

Answer 1

That's a very common mistake.

In a setter of a computed property the new value is represented by the implicit newValue variable, it's not the property itself.

set {
   let json = codeToJson(data: newValue)
   UserDefaults.standard.set(json, forKey: "key")
}