iOS has an undo function that works in a wide variety of apps and situations. But it doesn't have an on-screen button. Instead, shake your iPhone or iPad when you want to undo your last action.
Video Transcript (Click to Expand)
Did you know that your iPhone and iPad have an Undo function? Sometimes you see that appear above the keyboard. But even if you don't see it there's a way to undo with just a shake. A lot of people don't know this.
For instance, here I am in the Notes app. I'm going to delete this last word here. Uh oh, I didn't want to do that. So how do I undo? All you need to do is shake. You get this little Undo Typing thing here. I can Cancel or Undo and it puts back what I had there before.
It works in other cases too. For instance, here I've got a mail message. Say I go and let's delete it and I want to undo that. Well, the same shake will work there as well and will put back that message.
So it works in a variety of different apps and a variety of different situations. If you ever want to undo something and don't see an obvious Undo button on the screen anywhere just give your iPhone or iPad a shake and a lot of times you'll get this prompt to undo the action that you just did.