Deferred deep linking is an advanced feature in mobile app development that enhances the user experience by allowing users to be directed to a specific in-app location even if the app is not installed when the link is first clicked. This article will delve into the technical workings of deferred deep linking in iOS, discuss its implementation, and highlight potential benefits and challenges.

Understanding Deferred Deep Linking

Deferred deep linking is a mechanism that enables users who interact with a link to be taken to a specific page or view in an app once they install and open it for the first time. This is particularly useful in user acquisition campaigns, where it's vital to maintain context and seamlessly transition users from marketing materials to the app experience.

How Deferred Deep Linking Works

Here's a step-by-step process of how deferred deep linking typically works in iOS:

1. User Clicks the Link:
   • A user encounters a deep link in a promotion (e.g., web, email) and clicks on it.
2. App Presence Check:
   • The system checks if the app associated with the deep link is installed on the user's device.
3. App Not Installed:
   • If the app is not installed, the user is directed to the App Store to download it.
4. Link Information Storage:
   • The deep link information is stored on the server or using a universal link tracking system.
5. App Installation and First Launch:
   • After installation, the app is opened for the first time.
6. Retrieving Stored Data:
   • The app communicates with the server or the tracking system to retrieve the deferred deep link information that was stored earlier.
7. Navigating to the Specific View:
   • The app uses the retrieved data to navigate the user to the specific content or section intended by the original deep link.

Technical Implementation

iOS does not provide an out-of-the-box solution for deferred deep linking. Therefore, leveraging third-party services is a common practice. Here's a general approach to implementing deferred deep linking:

1. Prepare Your URLs:
   • Ensure your deep links are configured correctly, typically in correspondence with Apple's Universal Links.
2. Utilize a Deferred Deep Linking Service:
   • Services like Branch.io, Firebase Dynamic Links, or Adjust can simplify the process by providing SDKs that handle link creation, user redirection, and data storage/retrieval.
3. Handling URL in App Delegate:
   • When a user installs and opens the app, handle the URL logic in `application(_:continue:restorationHandler:)`. Here, you capture the deferred URL parameters.
   • Upon app installation, make a network call to retrieve the deferred deep link data based on a unique identifier, commonly a device-specific ID.
   • Define the logic to navigate the user based on the data you've retrieved, enhance their experience by directing them to the intended in-app location.

• Enhanced User Experience:
  • Maintains user interest by providing continuity from promotional content to app content without losing context.
• Improved Conversion Rates:
  • Removes friction in user acquisition funnels, effectively increasing the chance of conversion and user retention.
• Rich Analytics:
  • Allows businesses to track the source of installs and user behavior, which can offer valuable insights for marketing campaigns.
• Implementation Complexity:
  • Requires integration with third-party services and careful handling of different link cases and user behaviors.
• Dependency on Network:
  • Deferred deep linking relies on network calls to retrieve stored data, which might introduce latency or fail without a reliable internet connection.
• Apple's Privacy Policies:
  • With increased privacy regulations on iOS, ensure compliance with Apple's policies, especially around tracking and data sharing.