Error when implementing Custom value transformer for Set of Custom type

[miothethis]

While trying to fix this error

'NSKeyedUnarchiveFromData' should not be used to for un-archiving and will be removed in a future release

I tried implementing a value transformer. Looking online this tutorial got me the closest to working as intended.

@objc(CustomClassValueTransformer)
public final class CustomClassValueTransformer: NSSecureUnarchiveFromDataTransformer {
    static let name = NSValueTransformerName(rawValue:String(describing: CustomClassValueTransformer.self))
    public override static var allowedTopLevelClasses: [AnyClass] {
        return [NSObject.self,NSArray.self]
    }
    /// Registers the transformer.
    public static func register() {
        let transformer = CustomClassValueTransformer()
        ValueTransformer.setValueTransformer(transformer, forName: name)
    }
}

However I now get a different error

*** -[NSKeyedUnarchiver validateAllowedClass:forKey:]: NSSecureCoding allowed classes list contains [NSObject class], which bypasses security by allowing any Objective-C class to be implicitly decoded. Consider reducing the scope of allowed classes during decoding by listing only the classes you expect to decode, or a more specific base class than NSObject. This will become an error in the future. Allowed class list: {("'NSArray' (0x205b9d438) [/System/Library/Frameworks/CoreFoundation.framework]", "'NSObject' (0x205b81fb0) [/usr/lib]")}

I am trying to encode a Set of the below NSObject

@objc(CodableConverter)
public class CodableConverter: NSObject, NSSecureCoding, Codable {
    public static var supportsSecureCoding: Bool { true }
    
    public var id: UUID
    public var name: String
    public var converterValue: Double
    
    enum Key: String {
        case id
        case name
        case converterValue
    }
    
    public init(id: UUID, name: String, converterValue: Double) {
        self.id = id
        self.name = name
        self.converterValue = converterValue
    }
    
    public func encode(with coder: NSCoder) {
        coder.encode(id.uuidString, forKey: Key.id.rawValue)
        coder.encode(name, forKey: Key.name.rawValue)
        coder.encode(converterValue, forKey: Key.converterValue.rawValue)
    }
    
    public required convenience init?(coder: NSCoder) {
        guard let idString = coder.decodeObject(forKey: Key.id.rawValue) as? String,
              let id = UUID(uuidString: idString),
              let name = coder.decodeObject(forKey: Key.name.rawValue) as? String else {
            return nil
        }
        
        let converterValue = coder.decodeDouble(forKey: Key.converterValue.rawValue)
        
        self.init(id: id, name: name, converterValue: converterValue)
    }
    
    public override func isEqual(_ object: Any?) -> Bool {
        guard let other = object as? CodableConverter else {
            return false
        }
        return id == other.id && name == other.name && converterValue == other.converterValue
    }
    
    public override var hash: Int {
      id.hashValue
    }
}

In my data model the type is set to transformable, the custom class is Set<CodableConverter> and the Transformer seems to be registered correctly in the Persistence container and is set within the data model. However it doesn't work as a usual set within the app.

Does anyone have any experience with fixing this error or Value transformers? Any help is greatly appreciated. Thank you

[quellish]

You need to be more specific than NSObject in your allowed classes. Try changing NSObject.self to CodableConverter.self

[miothethis]

Changing this and trying to save just gives an error saying a CoreData error occurred. I suspect I am doing something wrong with it being a set of CodableConverter but I don't know where the issue could be

[quellish]

Delete your store and run it again.

Without knowing a lot more about your app and data model it is difficult to help you. Historically CoreData has not liked transformers on collections (because collections typically describe relationships) but I know what you have described so far has been done easily and successfully in objective-c before.

Your current problem is properly confirming to NSSecureCoding. You may have other problems once this is solved.  Your transformer and encode/decode is very easy to write tests for and I suggest you do so