Just want to discuss about a potential feature.

Unfortunately I think we cannot do "Trait Variation" for "User Defined Runtime Attributes"
So when we define something, it is for all ipads and iphones

I make a little PoC using NSDataAsset, that can be variated

A data asset named mask

Inside I put just some text file with the wanted value of a maskType

• iphone file contains: circle
• ipad file contains: ellipse

Then in MaskType I add a code to parse NSDataAsset

public extension MaskType {
  init(string: String?) {
....
case "dataAsset":
      if let name = params[safe: 0],
        let dataAsset = NSDataAsset(name: name),
        let value = String(data: dataAsset.data, encoding: .utf8) {
        self.init(string: value)
      } else {
        self = .none
      }

And finally I use it on my view in storyboard like this
dataAsset(mask)

on iphone a circle

on ipad an ellipse