5.swift

class ClassWrapper<T: ClassFamily, U: Decodable>: Decodable {
    /// The family enum containing the class information.
    let family: T
    // The decoded object. Can be any subclass of U.
    let object: U?

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: Discriminator.self)
        // Decode the family with the discriminator.
        family = try container.decode(T.self, forKey: T.discriminator)
        // Decode the object by initialising the corresponding type.
        if let type = family.getType() as? U.Type {
            object = try type.init(from: decoder)
        } else {
            object = nil
        }
    }
}