react native memory leak react navigation - react-native

Question

I want to check If the user has a secure Token in a useEffect but I get this error Message.
Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application.
This happens when I use the useEffect. If I remove it, then I get no error message but I need to check if the user has the token.
import React, { useEffect } from 'react';
import { View, Text } from 'react-native';
import getSecureKey from '../utilies/getSecureKey';
const Stack = createStackNavigator();
const AppStack = ({ navigation }) => {
useEffect(() => {
getSecureKey().then(res => console.log(res)).catch(e => console.log(e));
}, []);
return (
<Stack.Navigator showIcon={true} initialRouteName="AppTabs">
<Stack.Screen name="AppTabs" component={AppTabs} options={{headerTitle: () => <Header />, headerStyle: {
backgroundColor: '#fff'
}}} />
.....
getSecureToken:
import * as SecureStore from 'expo-secure-store';
const getSecureKey = async () => {
const key = await SecureStore.getItemAsync('jwt');
return key;
};
export default getSecureKey;
App.js
import React, { useState, useEffect } from 'react';
import * as Font from 'expo-font';
import { NavigationContainer } from '#react-navigation/native';
import AppLoading from 'expo-app-loading';
import { Provider } from 'react-redux';
import store from './src/redux/store/index';
import AppStack from './src/navigation/stack';
const getFonts = async () => {
await Font.loadAsync({
"nunito-regular": require("./assets/fonts/Nunito-Regular.ttf"),
"nunito-bold": require("./assets/fonts/Nunito-Bold.ttf"),
});
};
const App = () => {
const [fontsLoaded, setFontsLoaded] = useState(false);
if(fontsLoaded) {
return (
<Provider store={store}>
<NavigationContainer><AppStack /></NavigationContainer>
</Provider>)
} else {
return (<AppLoading startAsync={getFonts} onFinish={() => setFontsLoaded(true)} onError={() => {}} />)
}
};
export default App;

Answer 1

Don't restore token in the navigator. Instead do this -
Firstly, install expo-app-loading from here
Then, create a folder called navigation where your App.js is located. Then inside it create a File called AppNavigator.js.
Inside AppNavigator.js, paste this
import React, { useEffect } from 'react';
import { View, Text } from 'react-native';
import { createStackNavigator } from '#react-navigation/stack';
import getSecureKey from '../utilities/getSecureKey';
const Stack = createStackNavigator();
const AppNavigator = () => {
// Remove these Lines --
// useEffect(() => {
// getSecureKey()
// .then((res) => console.log(res))
// .catch((e) => console.log(e));
// }, []);
return (
<Stack.Navigator showIcon={true} initialRouteName="AppTabs">
<Stack.Screen
name="AppTabs"
component={AppTabs}
options={{
headerTitle: () => <Header />,
headerStyle: {
backgroundColor: '#fff',
},
}}
/>
</Stack.Navigator>
);
};
export default AppNavigator;
For your fonts create a folder called hooks where your App.js is located and inside that create a file useFonts.js
In useFonts.js write like this -
import * as Font from "expo-font";
export default useFonts = async () => {
await Font.loadAsync({
"nunito-regular": require("./assets/fonts/Nunito-Regular.ttf"),
"nunito-bold": require("./assets/fonts/Nunito-Bold.ttf"),
});
};
In your App.js
import React, { useState } from 'react';
import { Text, View, StyleSheet } from 'react-native';
import Constants from 'expo-constants';
import { NavigationContainer } from '#react-navigation/native';
import AppLoading from 'expo-app-loading';
import useFonts from "./hooks/useFonts";
import getSecureKey from './utilities/getSecureKey';
import AppNavigator from './navigation/AppNavigator';
export default function App() {
const [IsReady, SetIsReady] = useState(false);
// Always perform Token Restoration in App.js just to keep code clear.
const FontAndTokenRestoration = async () => {
await useFonts(); // Font is being loaded here
const token = await getSecureKey();
if (token) {
console.log(token);
}
};
if (!IsReady) {
return (
<AppLoading
startAsync={FontAndTokenRestoration}
onFinish={() => SetIsReady(true)}
onError={() => {}}
/>
);
}
return (
<NavigationContainer>
<AppNavigator />
</NavigationContainer>
);
}