One of my colleagues has an emacs flow to quickly land him in a new “experiment” project. He’s on backend, and I’m on iOS. I’ve used Swift Playgrounds for iOS a few times which is nice, but I never liked Xcode playgrounds as much. Most often I’ll just create a new test case in an app’s unit testing suite to do my experiment. This doesn’t work as well for UI experimentation, though. Usually I iterate right on the actual UI of my app, but it could definitely be worthwhile doing a simpler thing on its own before moving into the full-fledged existing UI. Certainly would help when filing a bug with Apple when they ask for a sample project...