Gruber is on a roll. In this Daring Fireball post, he digs into the iOS “Shake to Undo” gesture, an inelegant solution to a reasonably common and complex problem.

My favorite bit:

Here’s an anecdote I heard years ago about how Shake to Undo came to be. Scott Forstall charged the iOS team with devising an interface for Undo — everyone knew the iPhone should have it,1 but no one had a good idea how to do it. One engineer joked that they could just make you shake the iPhone to invoke it. Forstall said he loved the idea, and what was proposed as a joke has been with us as the Undo interface ever since.

My biggest issues with Shake to Undo are that it breaks flow (you have to stop whatever you were doing and shake your device like a maniac) and requires a physical action that is difficult for many people. I’d love to see this addressed as part of the architecture, as Undo is for the Mac.