Why does Apple always have a horizontal screen when texting in 4s?

Operation method:

1. Double-click the Home button, and you will see a multi-tasking user interface at the bottom of the main screen, and quickly slide from left to right with your finger;

2. Tap the screen lock icon to lock the screen vertically;

3. The small lock icon indicates that the screen is locked. Press it again to unlock the screen.

4. The small lock icon in the status bar indicates that gravity sensing is turned on.