Exploring React Native’s Flexbox Properties for Responsive App Design

Introduction

Wassup mobile geeks? We all know the importance of responsive mobile app designs and I am sure all of us have read enough about it. So today, I would like to express my thoughts on Flexbox and its imperative role in responsive app design.

What is Flexbox?

The Flexbox is used in React Native for controlling responsive UI and layouts. We are able to build any perplexing UI with all screen dimensions using flex concepts. Its characteristics allow us to effortlessly manipulate components. Flexbox is similar to CSS Flexbox, but with a few differences and limitations specific to the React Native environment.

Benefits of Using Flexbox

1. The design of the screen is responsive with flex.

2. Designs that are dynamic and adaptive UI can be easily expanded, shrink, or wrap with flex.

3. Alignments of elements can be arranged vertically or horizontally, uniformly distributed, or positioned at the beginning, middle, or end of the container.

4. Rearranging the components allows you to change the order of react native UI components elements without changing the component hierarchy behind them.

5. Using Flex in React Native we can have nested designs allowing you to build multifaceted UI structures inside of UI structures.

Key concepts and properties of Flexbox in React Native:

• Flex Direction

• Justify Content

• Align-Items

• Flex

• Flex Wrap

• Flex Grow

Flex Direction

Flexbox uses the flexDirection parameter in React Native to determine the primary axis along which components are laid out within a container. It defines whether the components should be lined either horizontally or vertically.

Various values are possible for the flexDirection property:

FlexDirection: row (default)

The components are arranged horizontally, from left to right. The main axis is horizontal and goes from left to right, whereas the cross axis is vertical and runs from top to bottom.

FlexDirection: column

The arrangement of the components is vertical, from top to bottom. The cross axis runs from left to right, and the main axis goes from top to bottom.

FlexDirection: row-reverse

Layout of the components is horizontal, going from right to left. The cross axis travels from top to bottom, while the main axis moves from right to left.

FlexDirection: column-reverse

The arrangement of the components is vertical, bottom to top. The cross axis runs from left to right, and the main axis goes from bottom to top.

Justify Content

React Native Flexbox uses the justifyContent property to regulate how components are aligned along a container’s main axis. It enables you to horizontally divide rooms between or around the components.

The following values have permissible for the justifyContent property:

JustifyContent: flex-start

aligns objects at the container’s start.

JustifyContent: flex-end

Aligns objects at the container’s end.

JustifyContent: center

Center the contents along the container’s principal axis.

JustifyContent: space-between

Equally distributes the elements along the primary axis. The initial thing lines up with the beginning, the last item lines up with the ending, and the space in between is evenly dispersed.

JustifyContent: space-around

Equally spaced-out views are distributed along the main axis. The gap between the items is half the size of the space before the first item and after the last item.

JustifyContent: space-evenly

Equivalent space is left between each item, including the space before and after the last item, as the objects are distributed uniformly along the main axis.

AlignItems

Flexbox in React Native uses alignitems to manage the alignment of items along a flex container’s cross-axis. When the flexDirection is set to “row” or “column,” it determines how the items are positioned both horizontally and vertically.

The following values have permissible for the alignItems property:

AlignItems: flex-start

Aligns items to the start axis. Items are aligned at the beginning of the container

AlignItems: flex-end

Aligns items to the end axis. Items are aligned at the end of the container.

AlignItems: center

Centers items along the cross axis within the container.

AlignItems: stretch

Items are stretched to fill the container’s cross axis. In cases when alignItems is not given, this is the default action.

AlignItems: baseline

Items are aligned according to their baseline. When the items have varying typefaces or heights, this is helpful.

Flex

The flex property in React Native is used to control how a component expands and fills available space within a flex container.

The flex property accepts a numeric value, which represents the proportion of available space that the component should occupy relative to other components within the same flex container. Higher values indicate that the component should expand more than components with lower values.

Tips:

Flex: 1  – It will cover whole screen area of the container

Example :
import React from ‘react’;
import {StyleSheet, View} from ‘react-native’;
const Flex = () => {
return (
<View style={styles.container}>
</View>
);
};
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: ‘red’
},
});

Output :

Flex 1 with 2 container will divide the view of same size and equal parts

Example:

import React from ‘react’;
import {StyleSheet, View} from ‘react-native’;
const Flex = () => {
return (
<View style={styles.container}>
<View style={{flex: 1, backgroundColor: ‘red’}} />
<View style={{flex: 1, backgroundColor: ‘blue’}} />
</View>
);
};
const styles = StyleSheet.create({
container: {
flex: 1
},
});

Flex 1 & Flex 2 with 2 container will divide the view of different size one with bigger and second will be smaller

Example:

import React from ‘react’;
import {StyleSheet, View} from ‘react-native’;
const Flex = () => {
return (
<View style={styles.container}>
<View style={{flex: 1, backgroundColor: ‘red’}} />
<View style={{flex: 2, backgroundColor: ‘blue’}} />
</View>
);
};
const styles = StyleSheet.create({
container: {
flex: 1
},
});

Here is Common example for flex:

import React from ‘react’;
import {StyleSheet, View} from ‘react-native’;
const Flex = () => {
return (
<View style={styles.container}>
<View style={{flex: 1, backgroundColor: ‘red’}} />
<View style={{flex: 2, backgroundColor: ‘dark orange’}} />
<View style={{flex: 3, backgroundColor: ‘green’}} />
</View>
);
};

const styles = StyleSheet.create({
container: {
flex: 1,
},
});

Output:

FlexWrap

The flexWrap property in React Native is used to determine whether or not flex items should wrap when their width or height exceeds that of the flex container. In cases where there is not enough room along the main axis, it controls how the flex elements are shown.

FlexWrap: nowrap

This is the default value. It indicates that flex items should not wrap and will be displayed in a single line, even if they overflow the container.

FlexWrap: wrap

This value allows flex items to wrap onto multiple lines if they exceed the container’s width or height along the main axis. The items will wrap to a new line, and additional lines will be created as needed.

FlexWrap: wrap-reverse

This value behaves similarly to wrap, but the wrapping occurs in the reverse order. The React Native flex items wrap onto multiple lines, but the order of the lines is reversed.

FlexGrow

The flexGrow property is used to manage how flex items within a flex container grow in relation to one another. When there is additional room available, it decides the percentage of the available space that each item should occupy along the main axis.

The relative growth factor of the flex item is represented by the flexGrow property, which accepts a number value. Greater values denote that the item should expand in comparison to other items contained in the same flexible container.

Example

import React from ‘react’;
import { View, StyleSheet } from ‘react-native’;

const App = () => {
return (
<View style={styles.container}>
<View style={[styles.item, { flexGrow: 1 }]}></View>
<View style={[styles.item, { flexGrow: 2 }]}></View>
<View style={[styles.item, { flexGrow: 3 }]}></View>
</View>
);
};
const styles = StyleSheet.create({
container: {
flex: 1,
flexDirection: ‘row’,
},
item: {
width: 50,
height: 50,
backgroundColor: ‘red’,
margin: 10,
},
});

Output:

Conclusion

Flexbox is essential in responsive app design as it enables developers to create flexible, adaptive, and efficient layouts that automatically adjust to different screen sizes. Its intuitive properties and behaviors simplify the design process and provide a consistent user experience across various devices and platforms.

We have other options like Screen Dimensions and other libraries for responsiveness but Flexbox is the best way to achieve responsive designs.

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