REACT NATIVE AND STATUS BAR

In this chapter, we will show you how to control the status bar appearance in React Native.

The Status bar is easy to use and all you need to do is set properties to change it.

The hidden property can be used to hide the status bar. In our example it is set to false. This is default value.

The barStyle can have three values – dark-content, light-content and default.

This component has several other properties that can be used. Some of them are Android or IOS specific. You can check it in official documentation.

App.js

import React, { Component } from 'react';
import { StatusBar } from 'react-native'

const App = () => {
   return (
      <StatusBar barStyle = "dark-content" hidden = {false} backgroundColor = "#00BCD4" translucent = {true}/>
   )
}
export default App

If we run the app, the status bar will be visible and content will have dark color.

Output

REACT NATIVE SWITCH

In this chapter, we will explain the Switch component in a couple of steps.

Step 1: Create File

We will use the HomeContainer component for logic, but we need to create the presentational component.

Let us now create a new file: SwitchExample.js.

Step 2: Logic

We are passing value from the state and functions for toggling switch items to SwitchExample component. Toggle functions will be used for updating the state.

App.js

import React, { Component } from 'react'
import { View } from 'react-native'
import SwitchExample from './switch_example.js'

export default class HomeContainer extends Component {
   constructor() {
      super();
      this.state = {
         switch1Value: false,
      }
   }
   toggleSwitch1 = (value) => {
      this.setState({switch1Value: value})
      console.log('Switch 1 is: ' + value)
   }
   render() {
      return (
         <View>
            <SwitchExample
            toggleSwitch1 = {this.toggleSwitch1}
            switch1Value = {this.state.switch1Value}/>
         </View>
      );
   }
}

Step 3: Presentation

Switch component takes two props. The onValueChange prop will trigger our toggle functions after a user presses the switch. The value prop is bound to the state of the HomeContainer component.

switch_example.js

import React, { Component } from 'react'
import { View, Switch, StyleSheet }

from 'react-native'

export default SwitchExample = (props) => {
   return (
      <View style = {styles.container}>
         <Switch
         onValueChange = {props.toggleSwitch1}
         value = {props.switch1Value}/>
      </View>
   )
}
const styles = StyleSheet.create ({
   container: {
      flex: 1,
      alignItems: 'center',
      marginTop: 100
   }
})

If we press the switch, the state will be updated. You can check values in the console.

Output

React Native - Text

In this chapter, we will talk about Text component in React Native.

This component can be nested and it can inherit properties from parent to child. This can be useful in many ways. We will show you example of capitalizing the first letter, styling words or parts of the text, etc.

Step 1: Create File

The file we are going to create is text_example.js

Step 2: App.js

In this step, we will just create a simple container.

App.js

import React, { Component } from 'react'
import TextExample from './text_example.js'

const App = () => {
   return (
      <TextExample/>
   )
}
export default App

Step 3: Text

In this step, we will use the inheritance pattern. styles.text will be applied to all Text components.

You can also notice how we set other styling properties to some parts of the text. It is important to know that all child elements have parent styles passed to them.

text_example.js

import React, { Component } from 'react';
import { View, Text, Image, StyleSheet } from 'react-native'

const TextExample = () => {
   return (
      <View style = {styles.container}>
         <Text style = {styles.text}>
            <Text style = {styles.capitalLetter}>
               L
            </Text>
            
            <Text>
               orem ipsum dolor sit amet, sed do eiusmod.
            </Text>
            
            <Text>
               Ut enim ad <Text style = {styles.wordBold}>minim </Text> veniam,
               quis aliquip ex ea commodo consequat.
            </Text>
            
            <Text style = {styles.italicText}>
               Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.
            </Text>
            
            <Text style = {styles.textShadow}>
               Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia
               deserunt mollit anim id est laborum.
            </Text>
         </Text>
      
      </View>
   )
}
export default TextExample

const styles = StyleSheet.create ({
   container: {
      alignItems: 'center',
      marginTop: 100,
      padding: 20
   },
   text: {
      color: '#41cdf4',
   },
   capitalLetter: {
      color: 'red',
      fontSize: 20
   },
   wordBold: {
      fontWeight: 'bold',
      color: 'black'
   },
   italicText: {
      color: '#37859b',
      fontStyle: 'italic'
   },
   textShadow: {
      textShadowColor: 'red',
      textShadowOffset: { width: 2, height: 2 },
      textShadowRadius : 5
   }
})

You will receive the following output −

REACT NATIVE AND HOW TO CREATE ALERTS

In this chapter, we will understand how to create custom Alert component.

Step 1: App.js

import React from 'react'
import AlertExample from './alert_example.js'

const App = () => {
   return (
      <AlertExample />
   )
}
export default App

Step 2: alert_example.js

We will create a button for triggering the showAlert function.

import React from 'react'
import { Alert, Text, TouchableOpacity, StyleSheet } from 'react-native'

const AlertExample = () => {
   const showAlert = () =>{
      Alert.alert(
         'You need to...'
      )
   }
   return (
      <TouchableOpacity onPress = {showAlert} style = {styles.button}>
         <Text>Alert</Text>
      </TouchableOpacity>
   )
}
export default AlertExample

const styles = StyleSheet.create ({
   button: {
      backgroundColor: '#4ba37b',
      width: 100,
      borderRadius: 50,
      alignItems: 'center',
      marginTop: 100
   }
})

Output

When you click the button, you will see the following −