The iPhone offers an automatic feature to clear the screen if the user spends some time without handling it. The function is fundamental to save battery, since the lit display is one of the items that consume more energy in the smartphone. However, the screen may not turn off or take a long time to automatically turn off.
Such situations can be resolved quickly, without having to download extra applications. Check out this step-by-step tutorial on how to solve the problem. Tests were done on Apple's iPhone 8 Plus with iOS 11.
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Option 1: by the screen settings
Step 1. Open the "Settings" menu and then touch "Screen and Brightness".
Access the Screen & Brightness menu in iPhone Settings
Step 2. Select the "Auto-lock" item and choose the time you prefer. It is worth remembering that it starts to count after the inactivity in the cell phone, so the shorter the interval, the greater battery savings. The "Never" item keeps the screen constantly on.
Select a short time for automatic screen lock on the iPhone
Option 2: by the general settings
Step 1. If the previous setting does not work, the system may be buggy with some configuration. To resolve this, go to the "Settings" item and then tap "General".
Select the General menu in the iPhone Settings
Step 2. Select "Reset" and then "Reset All Settings". This option will not erase your files, but will reset all settings you have modified on your phone. The iPhone starts to use factory settings, while other files and applications are preserved.
Reset all settings on iPhone
After zeroing, make sure the screen lockout time (first procedure) is within 30 seconds.
With information: Apple.com
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