How-To, Build Your Own App
Whether for personal use or for an entrepreneurial idea, building your own app can be an empowering, interesting, and most importantly fun way to spend your time.
In this article, we focus on how to build your own app from scratch, and all you need to bring with you is your imagination. We will use Expo, which simplifies mobile app development by providing a set of tools and services built around React Native. With Expo, you can write an app using JavaScript/TypeScript, test it in real-time, and deploy it to both iOS and Android app stores.
Why Expo? You don't need to write 2 different apps - just one that works on both platforms. If you're new to development, you can check out Expo and React Native documentation to learn more.
Key Takeaways
- Set up your development environment with Node.js, Expo CLI, and a code editor
- Create projects with 'npx create-expo-app' and test with Expo Go
- Build features using React Native components and JavaScript
- Test thoroughly and use Expo's debugging tools
- Export your app for iOS, Android, or web deployment
Before You Start
You'll need a computer (Windows, MacOS, or Linux) and an internet connection. Here's what you'll be doing:
- • Set up your development environment with necessary software
- • Create a simple To-Do List app as your first project
- • Test your app on a mobile device or emulator
- • Learn to enhance and customize your app
- • Export and share your completed app
Phase 1: Environment Setup
Get your computer ready for app development.
Set Up Your Environment
- •Install a code editor like Visual Studio Code for easier development
- •Download and install Node.js from nodejs.org (latest version)
- •Install Expo CLI globally using npm install -g expo-cli
- •Download Expo Go app on your phone from App Store or Google Play
Create Your New Project
- •Open terminal and navigate to your preferred directory
- •Run 'npx create-expo-app TodoApp' to create a new project
- •Choose the 'blank' template when prompted
- •Navigate to your project with 'cd TodoApp'
Terminal Commands:
npx create-expo-app TodoApp
cd TodoApp
npx expo startTest Your Project
- •Start your project with 'npx expo start' command
- •Scan the QR code with Expo Go app on your phone
- •Test on virtual device (Android Studio) or web browser
- •Verify the app loads successfully on your chosen platform
Phase 2: Building Your App
Now let's create your first functional app - a To-Do List.
Build Your App Features
- •Open your project folder in your code editor
- •Edit App.js to implement your app functionality
- •Use React Native components for UI elements
- •Test changes in real-time with live reloading
Code Example (App.js):
import React, { useState } from 'react';
import { StyleSheet, Text, View, TextInput, Button, FlatList } from 'react-native';
export default function App() {
const [task, setTask] = useState('');
const [taskList, setTaskList] = useState([]);
const addTask = () => {
if (task.trim()) {
setTaskList([...taskList, { id: Date.now().toString(), value: task }]);
setTask('');
}
};
return (
<View style={styles.container}>
<Text style={styles.title}>To-Do List</Text>
<TextInput
style={styles.input}
placeholder="Enter a task"
value={task}
onChangeText={setTask}
/>
<Button title="Add Task" onPress={addTask} />
<FlatList
data={taskList}
renderItem={({ item }) => (
<Text style={styles.taskItem}>{item.value}</Text>
)}
keyExtractor={(item) => item.id}
/>
</View>
);
}
const styles = StyleSheet.create({
container: {
flex: 1,
paddingTop: 50,
paddingHorizontal: 20,
backgroundColor: '#fff',
},
title: {
fontSize: 24,
fontWeight: 'bold',
marginBottom: 20,
},
input: {
borderWidth: 1,
borderColor: '#ccc',
padding: 10,
marginBottom: 10,
borderRadius: 5,
},
taskItem: {
fontSize: 18,
padding: 10,
borderBottomWidth: 1,
borderBottomColor: '#eee',
},
});Enhance Your App
- •Add delete functionality to remove completed tasks
- •Customize colors and styling for better visual appeal
- •Implement data persistence to save tasks between sessions
- •Add features like task completion status or due dates
Code Example (App.js):
// Enhanced version with delete functionality
renderItem={({ item }) => (
<View style={styles.taskItem}>
<Text>{item.value}</Text>
<Button
title="Delete"
onPress={() => setTaskList(taskList.filter((t) => t.id !== item.id))}
/>
</View>
)}
taskItem: {
flexDirection: 'row',
justifyContent: 'space-between',
alignItems: 'center',
padding: 10,
borderBottomWidth: 1,
borderBottomColor: '#eee',
},Phase 3: Testing & Publishing
Ensure your app works perfectly and share it with others.
Test and Debug
- •Test your app on multiple devices and platforms
- •Use Expo's built-in debugging tools and console
- •Check for errors in the terminal output
- •Shake your phone in Expo Go to access developer menu
Export Your App
- •Create an account at expo.dev for publishing
- •Login to Expo CLI with 'npx expo login'
- •Build for Android with 'npx expo build:android'
- •Build for iOS with 'npx expo build:ios' (Mac only)
Commands:
npx expo login
npx expo build:android
# or
npx expo build:ios
# For quick sharing:
npx expo publishDevelopment Tips & Best Practices
- 💡Use AI tools like GitHub Copilot to help generate code and catch errors
- 🔧Test your app on both iOS and Android devices for compatibility
- 📱Consider using Android Studio emulator if you don't have a physical Android device
- 🌐You can test web-only apps directly in your browser without mobile devices
- 🎨Experiment with styling and colors to make your app visually appealing
Final Notes
You've successfully set up your environment, built a simple app, and even tried it out. Next steps we will leave to your imagination. We hope you will find it interesting and most importantly fun to play with your code and build an app! If you need any assistance, let us know and our experts will help you bring your ideas to reality.