Network info and Building Standalone Apps
Network Info
A mobile device will usually be connected to a network. Sometimes the mobile device will lose connectivity, or be taken offline, or switch from one network type to another, such as from WiFi to Cellular or vice versa. It can be useful for a mobile app to know when a device’s network connection changes, so it can deal with network changes if necessary.
An app might support switching to offline operation, and possibly handle synchronizing changes with a remote server when the device reconnects to a network. An app might also want access to information about a network connection for other reasons, such as pausing large data transfers if a device is not WiFi.
React Native Community’s NetInfo Library
Originally a part of React Native, moved to a third party library maintained by the React Native Community organization.
You will install it with a scoped install, ex: yarn install@react-native-community/netinfo
This lets you know that this is an official package maintained by this organization
- NetInfo.fetch() – get current state of the network, returns a promise that resolves to a NetInfoState object
- NetInfo.addEventListener(NetInfoState => {…}) – subscribe to network changes, automatically gives you access to the NetInfoState object, returns a function that will unsubscribe this listener.
The NetInfoState object contains these following properties
Look at the different network connection types that can be recognized.
Network Info
- Learn to use the NetInfo library to obtain network information.
- Respond to changes in the network information by displaying a message using React Native’s ToastAndroid API for Android, or its Alert API for iOS.
- Install NetInfo using: expo install @react-native-community/netinfo@5
MainComponent.js
import React, { Component } from ‘react’;
import Home from ‘./HomeComponent’;
import Directory from ‘./DirectoryComponent’;
import CampsiteInfo from ‘./CampsiteInfoComponent’;
import About from ‘./AboutComponent’;
import Contact from ‘./ContactComponent’;
import Reservation from ‘./ReservationComponent’;
import Favorites from ‘./FavoritesComponent’;
import { View, Platform, StyleSheet, Text, ScrollView, Image, Alert, ToastAndroid } from ‘react-native’;
import { createStackNavigator } from ‘react-navigation-stack’;
import { createDrawerNavigator, DrawerItems } from ‘react-navigation-drawer’;
import { createAppContainer } from ‘react-navigation’;
import { Icon } from ‘react-native-elements’;
import SafeAreaView from ‘react-native-safe-area-view’;
import { connect } from ‘react-redux’;
import { fetchCampsites, fetchComments, fetchPromotions, fetchPartners } from ‘../redux/ActionCreators’;
import Login from ‘./LoginComponent’;
import NetInfo from ‘@react-native-community/netinfo’;
const mapDispatchToProps = {
fetchCampsites,
fetchComments,
fetchPromotions,
fetchPartners
};
const DirectoryNavigator = createStackNavigator(
{
Directory: {
screen: Directory,
navigationOptions: ({navigation}) => ({
headerLeft: <Icon
name=’list’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
},
CampsiteInfo: { screen: CampsiteInfo }
},
{
initialRouteName: ‘Directory’,
defaultNavigationOptions: {
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
}
}
}
);
const HomeNavigator = createStackNavigator(
{
Home: { screen: Home }
},
{
defaultNavigationOptions: ({navigation}) => ({
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
},
headerLeft: <Icon
name=’home’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
}
);
const AboutNavigator = createStackNavigator(
{
About: { screen: About }
},
{
defaultNavigationOptions: ({navigation}) => ({
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
},
headerLeft: <Icon
name=’info-circle’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
}
);
const ContactNavigator = createStackNavigator(
{
Contact: { screen: Contact }
},
{
defaultNavigationOptions: ({navigation}) => ({
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
},
headerLeft: <Icon
name=’address-card’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
}
);
const ReservationNavigator = createStackNavigator(
{
Reservation: { screen: Reservation }
},
{
defaultNavigationOptions: ({navigation}) => ({
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
},
headerLeft: <Icon
name=’tree’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
}
);
const FavoritesNavigator = createStackNavigator(
{
Favorites: { screen: Favorites }
},
{
defaultNavigationOptions: ({navigation}) => ({
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
},
headerLeft: <Icon
name=’heart’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
}
);
const LoginNavigator = createStackNavigator(
{
Login: { screen: Login }
},
{
defaultNavigationOptions: ({navigation}) => ({
headerStyle: {
backgroundColor: ‘#5637DD’
},
headerTintColor: ‘#fff’,
headerTitleStyle: {
color: ‘#fff’
},
headerLeft: <Icon
name=’sign-in’
type=’font-awesome’
iconStyle={styles.stackIcon}
onPress={() => navigation.toggleDrawer()}
/>
})
}
);
const CustomDrawerContentComponent = props => (
<ScrollView>
<SafeAreaView
style={styles.container}
forceInset={{top: ‘always’, horizontal: ‘never’}}>
<View style={styles.drawerHeader}>
<View style={{flex: 1}}>
<Image source={require(‘./images/logo.png’)} style={styles.drawerImage} />
</View>
<View style={{flex: 2}}>
<Text style={styles.drawerHeaderText}>NuCamp</Text>
</View>
</View>
<DrawerItems {…props} />
</SafeAreaView>
</ScrollView>
);
const MainNavigator = createDrawerNavigator(
{
Login: {
screen: LoginNavigator,
navigationOptions: {
drawerIcon: ({tintColor}) => (
<Icon
name=’sign-in’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
},
Home: {
screen: HomeNavigator,
navigationOptions: {
drawerIcon: ({tintColor}) => (
<Icon
name=’home’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
},
Directory: {
screen: DirectoryNavigator,
navigationOptions: {
drawerIcon: ({tintColor}) => (
<Icon
name=’list’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
},
Reservation: {
screen: ReservationNavigator,
navigationOptions: {
drawerLabel: ‘Reserve Campsite’,
drawerIcon: ({tintColor}) => (
<Icon
name=’tree’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
},
Favorites: {
screen: FavoritesNavigator,
navigationOptions: {
drawerLabel: ‘My Favorites’,
drawerIcon: ({tintColor}) => (
<Icon
name=’heart’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
},
About: {
screen: AboutNavigator,
navigationOptions: {
drawerLabel: ‘About Us’,
drawerIcon: ({tintColor}) => (
<Icon
name=’info-circle’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
},
Contact: {
screen: ContactNavigator,
navigationOptions: {
drawerLabel: ‘Contact Us’,
drawerIcon: ({tintColor}) => (
<Icon
name=’address-card’
type=’font-awesome’
size={24}
color={tintColor}
/>
)
}
}
},
{
initialRouteName: ‘Home’,
drawerBackgroundColor: ‘#CEC8FF’,
contentComponent: CustomDrawerContentComponent
}
);
const AppNavigator = createAppContainer(MainNavigator)
class Main extends Component {
componentDidMount() {
this.props.fetchCampsites();
this.props.fetchComments();
this.props.fetchPromotions();
this.props.fetchPartners();
NetInfo.fetch().then(connectionInfo => {
(Platform.OS === ‘ios’)
? Alert.alert(‘Initial Network Connectivity Type:’, connectionInfo.type)
: ToastAndroid.show(‘Initial Network Connectivity Type: ‘ +
connectionInfo.type, ToastAndroid.LONG);
});
this.unsubscribeNetInfo = NetInfo.addEventListener(connectionInfo => {
this.handleConnectivityChange(connectionInfo);
});
}
componentWillUnmount() {
this.unsubscribeNetInfo();
}
handleConnectivityChange = connectionInfo => {
let connectionMsg = ‘You are now connected to an active network.’;
switch (connectionInfo.type) {
case ‘none’:
connectionMsg = ‘No network connection is active.’;
break;
case ‘unknown’:
connectionMsg = ‘The network connection state is now unknown.’;
break;
case ‘cellular’:
connectionMsg = ‘You are now connected to a cellular network.’;
break;
case ‘wifi’:
connectionMsg = ‘You are now connected to a WiFi network.’;
break;
}
(Platform.OS === ‘ios’)
? Alert.alert(‘Connection change:’, connectionMsg)
: ToastAndroid.show(connectionMsg, ToastAndroid.LONG);
}
render() {
return (
<View style={{
flex: 1,
paddingTop: Platform.OS === ‘ios’ ? 0 : Expo.Constants.statusBarHeight
}}>
<AppNavigator />
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
},
drawerHeader: {
backgroundColor: ‘#5637DD’,
height: 140,
alignItems: ‘center’,
justifyContent: ‘center’,
flex: 1,
flexDirection: ‘row’
},
drawerHeaderText: {
color: ‘#fff’,
fontSize: 24,
fontWeight: ‘bold’
},
drawerImage: {
margin: 10,
height: 60,
width: 60
},
stackIcon: {
marginLeft: 10,
color: ‘#fff’,
fontSize: 24
}
});
export default connect(null, mapDispatchToProps)(Main);
Additional Resources:
- React Native Community – NetInfo
- React Native Community on Github
- React Native – ToastAndroid, Alert
