Deep linking basics in React Native

Introduction

Deep linking lets your app open specific screens directly from a link. This helps users jump right to what they want without extra steps.

You want users to open a product page directly from a web link.

You want to send notifications that open a specific app screen.

You want to share app content links with friends.

You want to handle special URLs that open your app.

You want to improve user experience by skipping the home screen.

Syntax

React Native

import { Linking } from 'react-native';

// To handle incoming links
Linking.addEventListener('url', handleUrl);

function handleUrl(event) {
  const url = event.url;
  // parse url and navigate
}

// To open a link
Linking.openURL('myapp://screen');

Use Linking.addEventListener('url', callback) to listen for links that open your app.

Use Linking.openURL() to open links from your app.

Examples

This listens for any link that opens the app and logs the URL.

React Native

Linking.addEventListener('url', (event) => {
  console.log('Opened with URL:', event.url);
});

This opens the app to the profile screen with ID 123 if deep linking is set up.

React Native

Linking.openURL('myapp://profile/123');

Sample App

This app listens for deep links and shows an alert with the URL when opened by a link. It also has a button to open a profile screen via a deep link.

React Native

import React, { useEffect } from 'react';
import { View, Text, Button, Linking, Alert } from 'react-native';

export default function App() {
  useEffect(() => {
    const handleUrl = (event) => {
      Alert.alert('Deep Link Opened', event.url);
    };

    Linking.addEventListener('url', handleUrl);

    return () => {
      Linking.removeEventListener('url', handleUrl);
    };
  }, []);

  const openProfile = () => {
    Linking.openURL('myapp://profile/42');
  };

  return (
    <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
      <Text>Welcome to Deep Linking Demo</Text>
      <Button title="Open Profile 42" onPress={openProfile} />
    </View>
  );
}

Important Notes

Remember to configure your app manifest (Android) and info.plist (iOS) to support your custom URL scheme.

Test deep links using command line tools or by clicking links on your device.

Always remove event listeners in cleanup to avoid memory leaks.

Summary

Deep linking lets users open specific app screens from links.

Use Linking API to listen and open URLs.

Configure your app to handle your custom URL schemes properly.

Practice

1. What is the main purpose of deep linking in a React Native app?

easy

A. To create animations between screens

B. To open specific screens in the app from external links

C. To improve app performance by caching data

D. To handle user authentication automatically

Solution

1. Step 1: Understand deep linking concept

   Deep linking allows apps to open specific screens directly from a URL or link.

2. Step 2: Identify the main purpose

   This helps users navigate directly to content without opening the app's home screen first.

3. Final Answer:

   To open specific screens in the app from external links -> Option B

4. Quick Check:

   Deep linking = open specific screens [OK]

Hint: Deep linking opens app screens from links [OK]

Common Mistakes:

• Confusing deep linking with app performance
• Thinking it handles animations
• Assuming it manages authentication

2. Which React Native API is used to listen for incoming deep links?

easy

A. AsyncStorage

B. Navigation

C. Linking

D. Animated

Solution

1. Step 1: Recall React Native APIs

   React Native provides the Linking API to handle URLs and deep links.

2. Step 2: Match API to deep linking

   Linking listens for URL events and opens the app screen accordingly.

3. Final Answer:

   Linking -> Option C

4. Quick Check:

   Linking API = deep link listener [OK]

Hint: Use Linking API to handle URLs [OK]

Common Mistakes:

• Choosing Navigation which manages screen transitions
• Confusing with AsyncStorage for data storage
• Picking Animated which is for animations

3. What will happen when this code runs and the app receives the URL myapp://profile/123?

Linking.addEventListener('url', (event) => {
  console.log(event.url);
});

medium

A. It logs 'myapp://profile/123' to the console

B. It throws a syntax error

C. It opens the profile screen automatically

D. It does nothing because the listener is incorrect

Solution

1. Step 1: Understand the event listener

   The code listens for 'url' events and logs the event.url string.

2. Step 2: Analyze the URL received

   When the app receives 'myapp://profile/123', the listener logs this exact string.

3. Final Answer:

   It logs 'myapp://profile/123' to the console -> Option A

4. Quick Check:

   Listener logs URL = correct output [OK]

Hint: Listener logs incoming URL string [OK]

Common Mistakes:

• Assuming it opens screen automatically without navigation code
• Thinking the code has syntax errors
• Believing the listener does nothing

4. Identify the error in this deep linking setup code:

Linking.addEventListener('url', handleUrl);

function handleUrl(event) {
  console.log(event);
}

// Later
Linking.removeEventListener('url', handleUrl);

medium

A. removeEventListener should be called with a different event name

B. addEventListener requires a second argument as a string

C. handleUrl function should return a value

D. removeEventListener is deprecated; use remove() on the subscription

Solution

1. Step 1: Check React Native Linking API usage

   In recent React Native versions, addEventListener returns a subscription object with a remove() method.

2. Step 2: Identify correct removal method

   removeEventListener is deprecated; you should call subscription.remove() instead.

3. Final Answer:

   removeEventListener is deprecated; use remove() on the subscription -> Option D

4. Quick Check:

   Use subscription.remove() not removeEventListener [OK]

Hint: Use subscription.remove() to stop listening [OK]

Common Mistakes:

• Calling removeEventListener which is deprecated
• Expecting handleUrl to return a value
• Passing wrong argument types to addEventListener

5. You want your React Native app to open the screen showing details for a product when a user clicks a link like myshop://product/42. Which steps are necessary to implement this deep linking behavior correctly?

hard

A. Configure URL scheme in app settings, listen for URL events, parse product ID, navigate to product screen

B. Only listen for URL events and log them; navigation happens automatically

C. Use AsyncStorage to save the URL, then read it on app start

D. Set up a web server to redirect links to the app

Solution

1. Step 1: Configure app to handle custom URL scheme

   You must set up your app to recognize 'myshop://' links in platform config files.

2. Step 2: Listen for URL events and parse the product ID

   Use Linking API to detect incoming URLs and extract the product ID from the URL path.

3. Step 3: Navigate to the product screen with the parsed ID

   Use your navigation library to open the product detail screen with the correct ID.

4. Final Answer:

   Configure URL scheme in app settings, listen for URL events, parse product ID, navigate to product screen -> Option A

5. Quick Check:

   Full deep linking setup = Configure URL scheme in app settings, listen for URL events, parse product ID, navigate to product screen [OK]

Hint: Setup scheme, listen URL, parse, navigate [OK]

Common Mistakes:

• Assuming navigation happens automatically without code
• Using AsyncStorage instead of URL handling
• Thinking a web server is needed for deep linking