1. For a few seconds, press and hold the Side/Power button until the Slide to Power Off message displays.
2. Drag the slider to completely turn off your iPhone.
3. Press and hold the Side/Power button for another 30 seconds, or until you see the Apple logo.
If your iPhone 8 Plus becomes stuck or frozen as a result of a Twitter app crash, you may need to force restart it. Here's how to do it:
1. Quickly press and release the Volume Up button.
2. Quickly press and release the Volume Down button.
3. Hold down the Side/Power button until the Apple logo appears.
Both of these reboots have no effect on any data or personal information saved on your iPhone's internal memory, so nothing will be lost.