public class User : NSObject, NSCoding {

    var username :String!
    var password :String!
    var userId :String!

    init(username :String, password :String) {
        self.username = username
        self.password = password
    }

    public func encode(with aCoder: NSCoder) {

        aCoder.encode(self.userId,forKey: "userId")
        aCoder.encode(self.username, forKey: "username")
        aCoder.encode(self.password, forKey: "password")
    }

    public required init?(coder aDecoder: NSCoder) {

        self.userId = aDecoder.decodeObject(forKey: "userId") as! String
        self.username = aDecoder.decodeObject(forKey: "username") as! String
        self.password = aDecoder.decodeObject(forKey: "password") as! String
    }

}