React Native save change switch with Async Storage - reactjs

Question

Im new in React Native, I have a problem with Switch, I want to save changes, dark mode and Switch, when I turn off the app and come back my changes should be saved. When I close the app, my switch came back to first position and dark mode does not work. I know that Im doing something wrong, but I did not mobile app and this is my first time and I dont know how to use AsyncStorage in this App to work this. Can somebody help me solve this problem?
import React, { createContext, useState, useEffect } from 'react';
import { AsyncStorage } from 'react-native';
export const DarkModeContext = createContext();
export default function DarkModeContextProvider(props) {
const [switchMode, setSwitchMode] = useState(false);
useEffect(() => {
let switch1 = switchMode;
AsyncStorage.setItem('switch1', JSON.stringify(switch1));
});
const SwitchThis = () => {
setSwitchMode(!switchMode);
};
return (
<DarkModeContext.Provider
value={{
switchMode,
SwitchThis
}}
>
{props.children}
</DarkModeContext.Provider>
);
}
and next component:
import React, { useState, useContext } from 'react';
import { View, ScrollView, TouchableOpacity, Text, AsyncStorage } from 'react-native';
import { List } from 'react-native-paper';
import BackgroundImage from './BackgroundImage';
import Clock from './Clock';
import TabIcon from './TabIcon';
import AddButton from './AddButton';
import { DarkModeContext } from './app-context';
const HomeScreen = () => {
const { switchMode } = useContext(DarkModeContext);
displayData = async () => {
try {
let switch1 = await AsyncStorage.getItem('switch1', function (err, switch1) {
JSON.parse(switch1)
}
)
return switch1
}
catch (error) {
return error
}
}
return (
<View
style={{
flex: 1,
backgroundColor: !switchMode ? 'white' : '#353535'
}}
>
<BackgroundImage fabButton={<AddButton/>}>
<Clock />
</BackgroundImage>
<ScrollView>
<List.Section>
<List.Subheader style={{ color: !switchMode ? 'black' : 'white' }}>
Task List
</List.Subheader>
<TouchableOpacity onPress={displayData}>
<Text>Click displayData</Text>
</TouchableOpacity>
</List.Section>
</ScrollView>
</View>
);
};

Answer 1

You are importing AsyncStorage from 'react-native' which is deprecated
use #react-native-community/react-native-async-storage
npm i #react-native-community/react-native-async-storage
And on your home screen you are not calling the function displayData() so how is data supposed to be displayed without function call.
and i do suggest making separate functions for writing and reading from async storage, it will help you reduce your code and time.
Like this:
let storeData=(name, obj)=> {
return new Promise((resolve,reject)=>{
let jsonOfItem = JSON.stringify(obj)
AsyncStorage.setItem(name, jsonOfItem).then(r=>resolve(jsonOfItem))
.catch(e=>reject(e))
})
}
let readData=(name)=> {
return new Promise((resolve,reject)=>{
//we want to wait for the Promise returned by AsyncStorage.setItem()
//to be resolved to the actual value before returning the value
AsyncStorage.getItem(name).then(r=> resolve(JSON.parse(r)) )
.catch(e=>reject(e))
})
}
//Now you can just read write easily in async function like this:
let fetchedData = await readData("key")
//and for storing data.
storeData("key",object)