Complete Guide to Universal Links

What Are Universal Links?

Universal links are URLs that work seamlessly across web and mobile apps. When a user taps a universal link on their iOS device, iOS checks if an app is installed that can handle that link. If the app is installed, it opens directly to the specific content. If not, the link opens in Safari.

On Android, the equivalent technology is called App Links. The concept is the same: one URL that intelligently routes users to either your app or your website.

How Universal Links Work

The process involves three key components:

iOS Universal Links Implementation

Step 1: Create the AASA File

Create a file called apple-app-site-association (no file extension) with this structure: apple-app-site-association

{
  "applinks": {
    "apps": [],
    "details": [
      {
        "appID": "TEAMID.com.yourcompany.yourapp",
        "paths": [
          "/products/*",
          "/articles/*",
          "/user/*"
        ]
      }
    ]
  }
}

Step 2: Configure Your iOS App

In Xcode, add the Associated Domains capability with your domain:

applinks:yourdomain.com
applinks:www.yourdomain.com

Step 3: Handle the URL in Your App

// AppDelegate.swift
func application(_ application: UIApplication,
                 continue userActivity: NSUserActivity,
                 restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void) -> Bool {
    
    guard userActivity.activityType == NSUserActivityTypeBrowsingWeb,
          let url = userActivity.webpageURL else {
        return false
    }
    
    // Handle the URL and navigate to appropriate screen
    handleUniversalLink(url)
    return true
}

Android App Links Implementation

Step 1: Create assetlinks.json

Host this file at https://yourdomain.com/.well-known/assetlinks.json:

[{
  "relation": ["delegate_permission/common.handle_all_urls"],
  "target": {
    "namespace": "android_app",
    "package_name": "com.yourcompany.yourapp",
    "sha256_cert_fingerprints": [
      "XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX"
    ]
  }
}]

Step 2: Update AndroidManifest.xml

<activity android:name=".MainActivity">
    <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" />
        <data android:host="yourdomain.com" />
        <data android:pathPrefix="/products" />
    </intent-filter>
</activity>

Step 3: Handle the Intent

// MainActivity.kt
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    
    val action = intent.action
    val data = intent.data
    
    if (Intent.ACTION_VIEW == action && data != null) {
        // Handle the deep link
        handleDeepLink(data)
    }
}

Best Practices & Common Pitfalls

Testing & Debugging

Analytics & Attribution

Proper analytics is crucial for understanding how your universal links perform. Track these key metrics:

• Click-through rates from different channels
• App open rate vs website visit rate
• User acquisition cost per channel
• Conversion rates for deep-linked content
• Time to first action after deep link
• Platform-specific performance (iOS vs Android)

Conclusion

Universal links are essential for modern mobile apps. They provide a seamless user experience, improve attribution, and work reliably across platforms. While implementation requires careful attention to detail, the benefits in user experience and analytics make it worthwhile.

Start with the basics, test thoroughly, and iterate based on real-world performance data. And if you want to skip the complexity, consider using a platform like Appy that handles all of this for you automatically.