Mastering iOS Deep Linking and Universal Linking: A Comprehensive Guide

What are Deep Links and Universal Links?

Deep Links in iOS

Deep Linking refers to a URL that brings users directly to specific content within an app, bypassing the app’s home screen. With deep linking, users can be navigated directly to the relevant content, enhancing user experience and engagement.

However, traditional deep links have limitations:

• They only work if the app is installed. If not, users encounter a broken link.

• For non-installed apps, deferred deep linking attempts to solve this issue, but it can be tricky.

Universal Links in iOS

Apple introduced Universal Links in iOS 9 to improve deep linking. Universal links:

• Allow users to open content in the app if it’s installed or fall back to the website if not.

• Are secure, as they require ownership of the domain.

• Prevent broken links by defaulting to web content when the app is not installed.

Universal links are recommended for most iOS deep-linking needs due to their flexibility and user experience benefits.

Implementing iOS Deep Links

1. Traditional Deep Linking Setup

For traditional deep linking, we use URL schemes, which are custom URL structures that launch the app and navigate to specific pages.

1. Define a Custom URL Scheme:

• In Xcode, open your project.

• Go to Info and add a new URL Types entry.

• Enter a unique URL Scheme, e.g., myapp.

2. Handle Deep Links in App Delegate:

Implement the application(_:open:options:) method in your AppDelegate.swift to handle the incoming URL.

func application(_ app: UIApplication,
                 open url: URL,
                 options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
    guard let components = URLComponents(url: url, resolvingAgainstBaseURL: true),
          let host = components.host else {
        return false
    }

    // Parse URL and navigate to specific part of the app
    if host == "page1" {
        // Navigate to Page1
    } else if host == "page2" {
        // Navigate to Page2
    }

    return true
}

With this setup, URLs like myapp://page1 will directly open the app and take users to Page1. However, these URLs only work if the app is already installed, which brings us to Universal Links.

Implementing Universal Links in iOS

1. Setting Up Apple App Site Association (AASA) File

Universal Links require the Apple App Site Association (AASA) file, hosted on your website.

1. Create the AASA file:

The apple-app-site-association file is a JSON file that specifies the paths in your domain that should open in your app.

{
  "applinks": {
    "apps": [],
    "details": [
      {
        "appID": "YOUR_TEAM_ID.com.yourdomain.appname",
        "paths": [ "/page1/*", "/page2/*" ]
      }
    ]
  }
}

2. Configure Associated Domains in Xcode:

• Go to your project settings, select your target, and go to Signing & Capabilities.

• Add the Associated Domains capability.

• Enter your domain prefixed with applinks:, like so:

applinks:yourdomain.com

3. Handle Universal Links in App Delegate:

Use application(_:continue:restorationHandler:) to handle universal link navigation.

func application(_ application: UIApplication,
                 continue userActivity: NSUserActivity,
                 restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void) -> Bool {
    guard userActivity.activityType == NSUserActivityTypeBrowsingWeb,
          let url = userActivity.webpageURL else {
        return false
    }

    // Handle universal link and navigate to content
    if url.path.contains("/page1") {
        // Navigate to Page1
    } else if url.path.contains("/page2") {
        // Navigate to Page2
    }

    return true
}

4. Testing Your Universal Links

• Install the app and try clicking the universal link on your iOS device.

• If the link redirects to the web, ensure your AASA file is correctly configured and served over HTTPS.

You can also use Apple’s Universal Links Validator to verify that your setup works.

Certainly! Here’s an updated section with links to each of the third-party services mentioned for iOS deep linking and universal linking.

Third-Party Services for Deep Linking and Universal Linking

Managing deep links and universal links can be complex, especially for large-scale apps with many links to maintain. Several third-party services provide comprehensive solutions for deep linking, universal linking, and deferred deep linking.

1. Branch.io

Branch is a popular deep linking solution that handles both deferred deep linking and universal linking. Key features include:

• Support for cross-platform linking.

• Powerful analytics on link clicks and installs.

• Deferred deep linking, allowing users to be taken to specific content after app install.

Branch simplifies setting up links for iOS and Android with advanced tracking and attribution.

2. Firebase Dynamic Links

Firebase Dynamic Links by Google offers a robust solution for creating smart links for both iOS and Android. Key features include:

• Auto-detection of platform (iOS, Android, or web).

• Deferred deep linking.

• Integration with other Firebase tools like Analytics and Cloud Messaging.

Firebase Dynamic Links is free and integrates well with Firebase’s ecosystem for tracking and notifications.

3. Adjust’s Deep Linking Solutions

Adjust provides deep linking as part of its app measurement platform, focusing on mobile marketing. Features include:

• Deferred deep linking and re-engagement.

• User-level analytics.

• Customizable link routing based on device, user behavior, or campaign.

Adjust’s deep linking works well for apps focused on marketing and retargeting.

4. AppsFlyer OneLink

AppsFlyer’s OneLink service specializes in marketing attribution and allows for deep linking across platforms. Notable features include:

• Multi-platform deep linking with user segmentation.

• Deferred deep linking and custom routing.

• Rich analytics for user acquisition and campaign performance.

AppsFlyer is ideal for marketers who need insights into link performance and user behavior.

5. Kochava

Kochava’s deep linking platform focuses on user engagement and marketing. Key features include:

• Cross-platform deep links and universal links.

• Deferred deep linking with user tracking.

• Integrations with other marketing and analytics tools.

Kochava is suited for companies needing precise attribution and deep linking for marketing purposes.

Each of these services offers robust capabilities for handling deep linking, deferred deep linking, and universal linking, making it easier to guide users through seamless navigation experiences across platforms.