Ever delete an email by mistake? Ever accidentally delete more text than you meant do (because the delete key goes faster and faster the longer you hold it)? Ever wish the iPhone had an Undo feature like the Mac does? Of course you have, and of course it does. It didn’t have one at first but it has one now. All you have to do is shake your iPhone to bring up a box asking you whether you want to undo whatever it is you did.
Shake it like a blackboard eraser. That works the best.
Advice: try it before you need it, so you see how it works.