The Accelerometer Interference Vector
The iPhone relies heavily on its internal gyroscope and accelerometer to understand how you are interacting with it. One of iOS’s oldest features is “Shake to Undo.” If you make a mistake while typing an email or deleting a photo, violently shaking the phone triggers an aggressive pop-up box asking if you want to undo your last action. While occasionally useful, the sensitivity of the accelerometer means that walking rapidly, riding over a bumpy road, or simply adjusting your grip frequently triggers this frustrating alert by accident.
How to Disable Shake to Undo
You can instruct the operating system to completely ignore these physical gestures, preventing the undo prompt from interrupting your workflow.
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 find the toggle switch labelled Shake to Undo.
5. Tap the toggle to switch it to the Off position (the switch will turn grey).
With this feature disabled, accidental movements will no longer trigger the disruptive pop-up box. If you make a genuine typing error, you can still easily undo your action by tapping the dedicated Undo button on the keyboard, or by swiping left with three fingers across the screen.