After changing screen brightness manually, the brightness cannot be changed from app code

Question

I'm using React Native with @adrianso/react-native-device-brightness library for this Imagine I'm in screen A, having device brightness about 0.5 When redirecting to screen B, Current brightness is saved, then I set brightness to 1 (maximum value). If I back to screen A, the brightness will be set back to saved value (0.5) This would work normally, until:

• In screen A, I swipe down and adjust screen brightness manually
• Redirect to screen B
• Vice versa

One of following scenarios would happen:

• Brightness is set to 1 in screen B, back to screen A still 1, not reset to 0.5
• Brightness is still 0.5 in screen B, not set to maximum as intended
• Brightness work normally as described above

I've tried:

• Changing library: other libraries have the same issue. Haven't tried expo-brightness
• Debug + logging: Try catch does not return any error, the saved brightness value and set new value are correct, it's just the screen brightness not changing following the set value.

By any means, is this issue related to the thread blocking of iOS?

Answer 1

const [previousBrightness, setPreviousBrightness] = useState<number | null>(null);

const getBrightness = () => {
    Brightness.getBrightnessAsync().then((value) => {
      setPreviousBrightness(value);
    });
};

 const restoreBrightness = useCallback(() => {
    if (previousBrightness !== null) {
      Brightness.setBrightnessAsync(previousBrightness)
        .then(() => {
          console.info('Brightness restored');
        })
        .catch(() => {
          console.error('Error restoring brightness');
        });
    }
  }, [previousBrightness]);




useEffect(() => {
(async () => {
  getBrightness();

  const { status } = await Brightness.requestPermissionsAsync();
  if (status === 'granted') {
    Brightness.setBrightnessAsync(1)
      .then(() => {
        console.info('Brightness set to 1');
      })
      .catch(() => {
        console.error('Error setting brightness');
      });
  }
})();
return restoreBrightness;
 },[restoreBrightness]);

1. store brightness at load
2. restore orignal brightness at unload