I am also blocked from using the posted solution with fetch(batchSize:) because it is broken when a model has non-optionals. https://developer.apple.com/forums/thread/762562?answerId=804245022#804245022

also note that it happens if any attribute in the model is required.

How do you recommend ModelActor observe changes in the results from the FetchDescriptor it uses to fetch?

While this works, it introduces a "bouncing" behavior, where the sheet resists being dismissed when dragged and bounces back to the top when released. This behavior is unfortunate when the view being presented uses drag gestures for its own purposes, as it conflicts. I'd be nice to be able to disable it. (filed as feedback: FB15247058)

Never mind my comment, it's possible to disable this bouncing behavior by using the .highPriorityGesture modifier for the presented view's gestures.