Universal Links and Android Deep Links: The Ultimate Guid

Absolutely! Here is a comprehensive, detailed blog post about Universal Links (iOS) and Deep Links (Android), including what they are, how they work, their benefits, implementation steps, best practices, and common pitfalls. This post is designed for developers, product managers, and anyone interested in improving mobile app navigation and user experience.

Universal Links and Android Deep Links: The Ultimate Guide

Introduction

Imagine clicking a link in an email or a social media post, and instead of being sent to a generic app home page or a website, you are taken straight to the exact content you wanted-maybe a product, a news article, or a special offer. This seamless navigation is made possible by deep linking technology, specifically Universal Links on iOS and App Links (deep links) on Android.

In this guide, we’ll explore:

• What deep links, Universal Links, and Android App Links are

• Why they matter for your app and users

• How to implement them step-by-step

• Best practices and common pitfalls

What Are Deep Links?

A deep link is a URL that opens a specific page or resource within a mobile app, rather than simply launching the app’s home screen. Deep links can be used in emails, SMS, social media, ads, or even QR codes.

Types of Deep Links

1. Traditional Deep Links (Custom URL Schemes)

   • Example: myapp://product/123

   • Opens the app if installed; does nothing if not.

   • Not secure, as any app can register the same scheme.

2. Universal Links (iOS) & App Links (Android)

   • Example: https://www.myshop.com/product/123

   • Opens the app if installed, otherwise loads the web page.

   • Secure, as they require domain verification.

   • Provide a seamless and consistent user experience.

Universal Links (iOS)

What Are Universal Links?

Universal Links are Apple’s standard for deep linking on iOS (introduced in iOS 9). They use standard HTTPS URLs, allowing users to move smoothly between web and app content.

How Universal Links Work

• When a user taps a Universal Link:

  • If the app is installed and registered for that domain, the app opens directly to the specified content.

  • If the app is not installed, the link opens in Safari or another browser, showing the web page.

• Users can always choose to open the link in Safari if they prefer.

Why Use Universal Links?

• Seamless experience: No annoying pop-ups or prompts.

• Security: Only verified apps can claim your domain.

• Fallback: Always opens the web page if the app isn’t installed.

• Analytics: Track user journeys across web and app.

Android Deep Links & App Links

What Are Android Deep Links?

Android supports two main types of deep links:

1. Traditional Deep Links (Custom Schemes):

   • Example: myapp://product/123

   • Opens the app if installed, otherwise fails silently.

2. Android App Links:

   • Example: https://www.myshop.com/product/123

   • Introduced in Android 6.0 (API level 23).

   • Uses HTTPS URLs and domain verification.

   • Opens the app if installed, otherwise opens the web page.

How Android App Links Work

• When a user taps an App Link:

  • If the app is installed and verified for that domain, the app opens to the specified content.

  • If not, the link opens in the browser.

• Users can set preferences for which app opens certain links.

Why Use App Links?

• Smooth transitions: Users go directly to the relevant content.

• Security: Domain verification prevents malicious apps from hijacking links.

• Fallback: Always opens the web page if the app isn’t installed.

Key Differences: Universal Links vs. Android App Links

Feature	Universal Links (iOS)	Android App Links
URL Format	HTTPS	HTTPS
Domain Verification	Apple App Site Assoc.	Assetlinks.json
Fallback	Web page	Web page
OS Version	iOS 9+	Android 6.0+
Security	High	High
User Experience	Seamless	Seamless

How to Implement Universal Links (iOS)

1. Register Associated Domains

• In your Xcode project, go to your app’s target → Signing & Capabilities.

• Add the Associated Domains capability.

• Add entries like: applinks:yourdomain.com

2. Create and Host the Apple App Site Association (AASA) File

• This is a JSON file named apple-app-site-association with no extension.

• Place it at https://yourdomain.com/apple-app-site-association

• Example content:

  json
  {
    "applinks": {
      "apps": [],
      "details": [
        {
          "appID": "TEAMID.com.yourcompany.yourapp",
          "paths": [ "/product/*", "/news/*" ]
        }
      ]
    }
  }
  

• The file must be served over HTTPS with a Content-Type: application/json.

3. Handle Universal Links in Your App

• Implement the application(_:continue:restorationHandler:) method in your AppDelegate.

• Parse the URL and navigate to the right screen.

4. Test Your Universal Links

• Use real devices (not simulators) for testing.

• Tap links in emails, messages, or browsers.

How to Implement Android App Links

1. Add Intent Filters in AndroidManifest.xml

xml
<intent-filter android:autoVerify="true">
    <action android:name="android.intent.action.VIEW" />
    <category android:name="android.intent.category.DEFAULT" />
    <category android:name="android.intent.category.BROWSABLE" />
    <data android:scheme="https"
          android:host="www.myshop.com"
          android:pathPrefix="/product/" />
</intent-filter>

2. Create and Host the Asset Links File

• Create a file named assetlinks.json and host it at:
  https://www.myshop.com/.well-known/assetlinks.json

• Example content:

  json
  [
    {
      "relation": ["delegate_permission/common.handle_all_urls"],
      "target": {
        "namespace": "android_app",
        "package_name": "com.mycompany.myapp",
        "sha256_cert_fingerprints": [
          "12:34:56:78:...:AB:CD"
        ]
      }
    }
  ]
  

3. Handle Incoming Intents

• In your activity, handle the intent and parse the URL to navigate to the correct content.

4. Test Your App Links

• Use the adb tool or tap links in real-world scenarios.

Best Practices for Deep Linking

• Always provide a fallback: Make sure users can access your content even if the app isn’t installed.

• Verify your domains: Both Apple and Google require domain verification for security.

• Keep URLs consistent: Use the same URL structure for web and app content.

• Test thoroughly: Deep linking can behave differently across devices and OS versions.

• Track user journeys: Use analytics to see how users interact with deep links.

Common Pitfalls

• Incorrect file hosting: Apple and Google require files to be hosted at specific locations with correct headers.

• Forgetting to update certificates: If your app’s signing certificate changes, update your verification files.

• Not handling edge cases: Users might uninstall and reinstall the app, change devices, or use unsupported browsers.

• Ignoring user preferences: Users can override app link handling in their device settings.

Conclusion

Universal Links and Android App Links are powerful tools for delivering a seamless, user-friendly experience. They connect your users directly to the content they care about, whether they’re coming from the web, an email, or another app. By implementing deep linking correctly, you’ll boost engagement, retention, and satisfaction.

If you’re building or managing a mobile app, investing the time to set up Universal Links and App Links is well worth it. Not only will your users thank you, but your business will benefit from smoother journeys and higher conversions.

Ready to get started?
Make sure your app and website are ready for deep linking, and start delivering the seamless experience your users expect!

Happy coding!

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