It’s no secret that typing on the iPhone and iPad is way slower, more difficult, and more error-prone than typing on a Mac’s real keyboard. But on the Mac when you make a mistake, you can hit Command-Z to undo in the blink of an eye. On an iOS device, you can usually undo typed mistakes, but the process is different—you physically shake the device, and then tap the Undo button that appears. (Tap Cancel if you’ve shaken the iPhone accidentally.) Shaking once is enough; you’re not trying to get the last bit of ketchup out. It’s a little easier to do with the iPhone than the iPad, but either way, make sure to hold on tight while shaking! On the iPad, happily, there’s a dedicated Undo button in the upper left corner of the keyboard and even an Undo key on the numeric keyboard. iPhones have the Undo button only in landscape mode.