The Accidental Deletion Vector
The iPhone includes a legacy accessibility feature known as “Shake to Undo.” If you type a long paragraph of text, or accidentally delete an email, physically shaking the handset will trigger a pop-up window offering to undo your last action. While conceptually useful, this feature is incredibly prone to accidental activation. If you simply pick up the phone too quickly, or if you are riding in a bumpy vehicle while attempting to type, the iPhone will violently throw an “Undo Typing” prompt onto the screen, frequently resulting in the accidental deletion of your work.
How to Disable Shake to Undo
You can instruct the iOS operating system to completely ignore the accelerometer when typing, ensuring the undo prompt never appears unless you manually request it.
1. Open the Settings app on your iPhone.
2. Scroll down and tap on Accessibility.
3. Under the Physical and Motor section, tap on Touch.
4. Scroll down until you locate the setting labelled Shake to Undo.
5. Tap the toggle to switch it to the Off position (the switch will turn grey).
Your iPhone will no longer respond to physical shaking. If you still need to undo a typing mistake, you can use the more reliable software method: simply swipe left across the screen with three fingers simultaneously to trigger the undo action.