Is your iPhone or iPad screen turning off before you've finished what you're doing? Try changing your auto-lock setting to give your device a little more patience.
To adjust your screen's auto-lock setting, start by opening your Settings menu and scrolling down to Display & Brightness.
Scroll down on the Display & Brightness
page and tap
On this page, you can decide how long you want your screen to stay on. If you select 'never', the screen will only turn off if you hit the power button.
Otherwise, it will stay lit for however long you set from the last moment you touch the screen.
Keep in mind that, while it may be more convenient to go with a longer time, it will drain your battery much faster.