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 which 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 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 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 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 init to make our React Native App. Assuming that you have node installed, you can use npm to install the react-native-cli command line utility. Open the terminal and go to the workspace and run

npm install -g react-native-cli

Run the following commands to create a new React Native project

react-native init ProjectName

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

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

react-native init ProjectName --version react-native@next

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 dependency into your node_module directory.

CocoaPods Installation

After the updation of React Native 0.60, they have introduced autolinking so we do not require to link the library but need to install pods. So to install pods use

cd ios && pod install && cd ..

Code

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

App.js

//This is an example code for Net Info// 
import React, { Component } from 'react';
//import react in our code.
 
import NetInfo from '@react-native-community/netinfo'
import { AppState, Text } from 'react-native';
 
export default class App extends Component {
  state = {
    appState: AppState.currentState,
  };
  componentDidMount() {
    //To get the network state once
    NetInfo.fetch().then(state => {
      console.log(
         'Connection type: ' + 
          state.type + 
         ', Is connected?: ' + 
          state.isConnected);
    });
    
    //Subscribe to network state updates
    const unsubscribe = NetInfo.addEventListener(state => {
      console.log(
         'Connection type: ' + 
          state.type + 
         ', Is connected?: ' + 
          state.isConnected);
    });

    //To Unsubscribe the network state update
    //unsubscribe();
  }
  render() {
    return (
      <Text style={{ marginTop: 30, padding: 20 }}>
        NetInfo Example. Please open debugger to see the log
      </Text>
    );
  }
}

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

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

react-native run-android

or on the iOS Simulator by running

react-native run-ios (macOS only).

Output Screenshots

Output in Online Emulator

That was the React Native NetInfo. 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. 🙂