2D Target Tracking w/ ARKit

We're looking for a way to do 2D image tracking for integration with ARKit.

Ideally, we'd like to be able let users draw their own images to track, but we're also willing to scale back to using predefined images that users can print out.

We've looked at Vuforia and it doesn't integrate with ARKit yet so that isn't a viable solution.

We really appreciate any recommendations to libraries you all have!

I don't understand what you mean. Should users draw by touching the screen of your app and the drawing should appear on a 2D plane in AR? Or do you want the app to recognise your real hands or a pencil and recognise what the user is drawing? :?