Unlock the Power of Progress Bars in React Native

What is a Progress Bar?

A progress bar is a visual representation of a task’s progress, providing users with essential information about the status of an operation. It can be used to display the progress of various tasks, such as downloading, file transfers, installations, and more.

Building a Determinate Progress Bar in React Native

While there are existing packages for progress bars in React Native, creating a custom one allows you to tailor it to your specific needs. In this article, we’ll guide you through building a determinate progress bar from scratch.

Getting Started

To begin, ensure you’re familiar with React Native and React Hooks. Use Expo CLI or React Native CLI to bootstrap your project. For this example, we’ll use Snack to build our progress bar directly in a web browser.

Designing the Progress Bar

A simple progress bar typically consists of descriptive text, a progress indicator, and a percentage completion display. Let’s create the skeleton of our progress bar by adding the following code to App.js:

import React from 'eact';
import { View, Text } from 'eact-native';

const ProgressBar = () => {
  return (
    
      Downloading...
      
        
      
      0%
    
  );
};

export default ProgressBar;

Styling the Progress Bar

To display the progress bar correctly, we need to adjust the container styling to align the child components in a column. Add the flexDirection: 'column' property to your container styles.

container: {
  flex: 1,
  justifyContent: 'center',
  alignItems: 'center',
  flexDirection: 'column',
}

Adding the Progress Counter

To display changing completion, we’ll add a counter using setInterval. This will increment the count Hook by 5 every second.

import { useState, useEffect } from 'eact';

const ProgressBar = () => {
  const [count, setCount] = useState(0);

  useEffect(() => {
    const intervalId = setInterval(() => {
      setCount(count + 5);
    }, 1000);

    return () => clearInterval(intervalId);
  }, [count]);

  return (
    
  );
};

Animating the Progress Bar

To animate our progress bar, we’ll create an animated value using the useRef Hook. This will help us animate the loader value.

import { useRef, useEffect } from 'eact';
import { Animated } from 'eact-native';

const ProgressBar = () => {
  const loader = useRef(new Animated.Value(0)).current;

  useEffect(() => {
    Animated.timing(loader, {
      toValue: count,
      duration: 1000,
    }).start();
  }, [count]);

  return (
    
  );
};

The Final Product

After adding the interpolated width to the animated progress bar and updating the percentage progress value, our progress bar is complete!

Take Your Progress Bar to the Next Level

While this is a basic progress bar, there are many improvements you can make, especially regarding animation. Try uploading a file and displaying the progress to challenge yourself further.

• Experiment with different animation styles and timing functions.
• Use a more advanced progress counter that takes into account the actual progress of the task.
• Style your progress bar to fit your app’s design.

View the final product