NSCoding Strongly API.swift

import Foundation

protocol ValueRepresentable: RawRepresentable {
    
    func value() -> String
}

extension ValueRepresentable {
    
    func namespaced<T: RawRepresentable>(_ key: T) -> String {
        return "\(Self.self).\(key.rawValue)"
    }
    
    func value() -> String {
        return namespaced(self)
    }
}

enum CodingKey: String, ValueRepresentable {

    //here you have the properties you can code
    case isUserLoggedIn
    case userIdentifier
}

extension NSCoder {

    //this is an example to encode a bool
    func encode(_ bool: Bool, forKey key: CodingKey) {
        encode(bool, forKey: key.value())
    }
    
    func decodeBool(forKey key: CodingKey) -> Bool {
        print(key.value())
        return decodeBool(forKey: key.value())
    }
    
    //do the same with other types
}

class Test: NSCoding {
    
    var isUserLoggedIn = false
    
    required init?(coder aDecoder: NSCoder) {
        
        isUserLoggedIn = aDecoder.decodeBool(forKey: .isUserLoggedIn)
    }
    
    func encode(with aCoder: NSCoder) {
        
        aCoder.encode(true, forKey: .isUserLoggedIn)
    }
}