I watched objc.io Swit Talk Episode 27, Typed Notification Part 1. I just learned there is a notification for PlaygroundPage.current.needsIndefiniteExecution change. It is called "PlaygroundPageNeedsIndefiniteExecutionDidChangeNotification". It’s super duper long. I think I can’t type it correctly without typo!!! This Swift Talk is about how to wrap these notifications to use them with type safety. Cool technique!