Storing structures with reference type properties

[NSExceptional]

The JSON object mapping library I've been working on is finally complete enough that I've started using it to replace Codable in another project of mine. I've just run into this issue when running my old tests though: arrays are not copied safely. I think this also means I'm not properly storing any struct (and enum!) with reference type properties.

Right now, I use this extension to create instances of custom struct types:

extension StructMetadata {
    func createInstance(props: [String: Any] = [:]) -> Any {
        // This allocates the necessary space for an instance of the given type
        var box = AnyExistentialContainer(metadata: self)
        for (key, value) in props {
            // Retain object values as needed since they are not
            // retained when stored via this method and passed as Any
            Unmanaged.retainIfObject(value)
            self.set(value: value, forKey: key, pointer: box.getValueBuffer())
        }
        
        return box.toAny
    }
}

Basically, I retain things that are objects and do a bitwise copy of every value for each key. I'm not sure what's going on below, the debugger just looks crazy. I'm guessing the array storage is being released since I'm not doing any manual retains for reference-type keys of structures—Person is a struct here.

After being constructed

After being copied (passed to a function)

Trying to print the array yields this:

Printing description of a.kids:
▿ 3 elements

I'm guessing I just need to do manual retains of reference type keys of custom structs. That seems like a lot of work though, is there anything in the runtime that can do this for me? Or is there a flag in the metadata that tells me when I need to do it so I can avoid enumerating the keys of every single struct type? Etc