How to conform a custom object to Codable

Question

I've been trying to save a UserData object so that content is "permanent". All of the methods online show classes with primitive types like String, Int, Double, etc. I am aware that you can store Data types but I couldn't find much

This is the class I want to save to disk. It errors out with : "Type 'UserData' does not conform to protocol 'Decodable'" and "Type 'UserData' does not conform to protocol 'Encodable'"

Obviously, skillBag is causing the issue; but I can't find any resources on how to conform Skill to Codable.

class UserData : ObservableObject, Codable{
    private var userName:String;
    @Published private var skillBag:[Skill] = [];
    
    init(Username user:String, skillBag skills:[Skill]) {
        userName = user;
        skillBag = skills;
    }
 }

Skill Class

class Skill : Identifiable, ObservableObject, Equatable{
    @Published var skillName:String = "";
    @Published var level:Int = 1;
    @Published var prestiege:Int = 0;
    var curXP:Double = 0.0;
    var maxXP:Double = 50.0;
    @Published var skillDesc:String;
    @Published public var skillColor:Color = Color.purple;
    @Published public var buttons: [SkillButton] = [];
    @Published private var prestCap:Int;

    //EXTRA HIDDEN CODE

}

For Reference, here is the SkillButton Class

class SkillButton : Identifiable, ObservableObject, Equatable{

    
    @Published public var xp:Double = 0;
    @Published private var buttonName:String = "";
    @Published private var uses:Int = 0;
    @Published public var buttonColor:Color = Color.pink;
    @Published private var description:String;

    enum CodingKeys: String, CodingKey {
        case buttonName, xp, uses, buttonColor, description
    }
    
    init(ButtonName buttonName:String, XpGained xp:Double, Uses uses:Int = 0, Description desc:String = "") {
        self.xp = xp;
        self.buttonName = buttonName;
        self.uses = uses;
        self.description = desc;
    }
}

I know that each of these classes need to conform to Codable, but I just couldn't find a resource to make these conform to Codable.

Answer 1

Other than not conforming the Skill and SkillButton classes to Codable, the underlying problem you have is down to the @published property wrapper, as this stops the auto-synthesis of Codable conformance.

Rather than writing out the solution, can I refer you to this Hacking with Swift link: https://www.hackingwithswift.com/books/ios-swiftui/adding-codable-conformance-for-published-properties

You will also have to conform Color to Codable yourself as (unless it's changed in recent updates?) it isn't Codable out of the box.