React Native NetInfo

React Native NetInfo

Here is an example of React Native NetInfo. React Native NetInfo exposes information about online/offline status. NetInfo notifies continuously about the network state whether it is online or offline.

Information about the net connection is very helpful when you are making an application that only works in online mode. The best example that you have seen is the YouTub app which will run smoothly and if you unexpectedly go offline it generates a bottom snack alert to notify you about the offline state.

Note: While getting internet connection information using NetInfo we attach a call-back function with it. NetInfo provides the network information in this callback function but we can’t say it will call the function once or twice so there is no pattern that can define the number of calls from the NetInfo. Yeah, it is very sure it will call the function immediately after the network state changes but still can say it will inform just once so you have to make your own logic with React Native state to handle the situation.

In this example, we will print the state of the internet connection on the console.

To Import NetInfo in Code

import NetInfo from '@react-native-community/netinfo'

To Get the Network State Once

NetInfo.getConnectionInfo().then((connectionInfo) => {
  console.log(
     'Initial, type: ' + 
      connectionInfo.type + 
     ', effectiveType: ' + 
      connectionInfo.effectiveType);
});

Subscribe to Network State Updates

const unsubscribe = NetInfo.addEventListener(state => {
  console.log(
     'Connection type: ' + 
      state.type + 
     ', Is connected?: ' + 
      state.isConnected);
});

To Unsubscribe from the Network State Update

unsubscribe();

To Make a React Native App

Getting started with React Native will help you to know more about the way you can make a React Native project. We are going to use react native command line interface to make our React Native App.

If you have previously installed a global react-native-cli package, please remove it as it may cause unexpected issues:

npm uninstall -g react-native-cli @react-native-community/cli

Run the following commands to create a new React Native project

npx react-native init ProjectName

If you want to start a new project with a specific React Native version, you can use the --version argument:

npx react-native init ProjectName --version X.XX.X

Note If the above command is failing, you may have old version of react-native or react-native-cli installed globally on your pc. Try uninstalling the cli and run the cli using npx.

This will make a project structure with an index file named App.js in your project directory.

Installation of Dependency

To use NetInfo we need to install @react-native-community/netinfo dependency.

To install this open the terminal and jump into your project using

cd ProjectName

Run the following command to install

npm install @react-native-community/netinfo --save

This command will copy all the dependencies into your node_module directory.

CocoaPods Installation

Please use the following command to install CocoaPods

npx pod-install

Code

Open App.js in any code editor and replace the code with the following code

App.js

// React Native NetInfo
// https://aboutreact.com/react-native-netinfo/

// import React in our code
import React, {useState, useEffect} from 'react';

// import all the components we are going to use
import {
  SafeAreaView,
  StyleSheet,
  View,
  Text,
  Button
} from 'react-native';

import NetInfo from '@react-native-community/netinfo';

const App = () => {
  const [netInfo, setNetInfo] = useState('');
  useEffect(() => {
    // Subscribe to network state updates
    const unsubscribe = NetInfo.addEventListener((state) => {
      setNetInfo(
        `Connection type: ${state.type}
        Is connected?: ${state.isConnected}
        IP Address: ${state.details.ipAddress}`,
      );
    });

    return () => {
      // Unsubscribe to network state updates
      unsubscribe();
    };
  }, []);

  const getNetInfo = () => {
    // To get the network state once
    NetInfo.fetch().then((state) => {
      alert(
        `Connection type: ${state.type}
        Is connected?: ${state.isConnected}
        IP Address: ${state.details.ipAddress}`,
      );
    });
  };

  return (
    <SafeAreaView style={{flex: 1}}>
      <View style={styles.container}>
        <Text style={styles.header}>
          React Native NetInfo
          {'\n'}
          To Get NetInfo information
        </Text>
        <Text style={styles.textStyle}>
          {/*Here is NetInfo to get device type*/}
          {netInfo}
        </Text>
        <Button
          title="Get more detailed NetInfo"
          onPress={getNetInfo}
        />
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'white',
    padding: 10,
    justifyContent: 'center',
  },
  header: {
    fontSize: 22,
    fontWeight: '600',
    color: 'black',
    textAlign: 'center',
    paddingVertical: 20,
  },
  textStyle: {
    marginTop: 30,
    fontSize: 16,
    textAlign: 'center',
    color: 'black',
    paddingVertical: 20,
  },
});

export default App;

Permission to Access Network State and other configurations for Android

We are accessing the network state so we need to add some permission in AndroidManifest.xml file (For Android) after ejecting the project from the expo environment.  On devices before SDK version API 23, the permissions are automatically granted if they appear in the manifest but after SDK version 23 android applies a new permissions model. For more about the permission, you can see React Native Android Permission.

So we are adding going to add the following permission in the AndroidMnifest.xml

<uses-permission
    android:name="android.permission.ACCESS_NETWORK_STATE"
/>

By adding permission in AndroidManifest.xml you are able to access ACCESS_NETWORK_STATE of your devices.

To Run the React Native App

Open the terminal again and jump into your project using.

cd ProjectName

1. Start Metro Bundler

First, you will need to start Metro, the JavaScript bundler that ships with React Native. To start Metro bundler run following command

npx react-native start

Once you start Metro Bundler it will run forever on your terminal until you close it. Let Metro Bundler run in its own terminal. Open a new terminal and run the application.

2. Start React Native Application

To run the project on an Android Virtual Device or on real debugging device

npx react-native run-android

or on the iOS Simulator by running (macOS only)

npx react-native run-ios

Output Screenshots

   

Output in Online Emulator

That was the React Native NetInfo. If you want to explore more options then you can also see react-native-offline, it supports iOS, Android and Windows.

If you have any doubts or you want to share something about the topic you can comment below or contact us here. The remaining components will be covered in the next article. Stay tuned!

Hope you liked it. 🙂