useAnimateOpacityOnValueChange.tsx

export const useAnimateOpacityOnValueChange = (
  valueToWatchForChange: boolean,
  trueOpacityValue: number = 1,
  falseOpacityValue: number = 0.4
) => {
  const calculateOpacity = (val: boolean) =>
    valueToWatchForChange ? trueOpacityValue : falseOpacityValue;
  
  const opacityAnimatedValue = useRef(
    new Animated.Value(calculateOpacity(valueToWatchForChange))
  ).current;
  
  useEffect(() => {
    Animated.timing(opacityAnimatedValue, {
      toValue: calculateOpacity(valueToWatchForChange),
      duration: 300,
      useNativeDriver: true
    }).start();
  }, [valueToWatchForChange]);
  
  return [opacityAnimatedValue];
};