Deep linking has become an essential tool for connecting the fragmented world of mobile apps into a more seamless and interconnected ecosystem. However, as a recent issue with the popular cryptocurrency wallet app Trust Wallet on iOS demonstrates, the world of deep linking is not without its complications and controversies.
In this in-depth article, we‘ll explore what deep linking is, how it works on a technical level, and why it has become so important for app developers and marketers. We‘ll also delve into the specifics of the Trust Wallet situation and what it means for the future of crypto apps on mobile. Finally, we‘ll examine some of the broader applications and implications of deep linking, including its role in marketing attribution, augmented reality, and the decentralized web.
What is Deep Linking?
At its core, deep linking is a way to link to specific content or functionality within a mobile app, rather than just launching the app‘s main screen. Just as web URLs allow you to link to individual pages on a website, deep links allow you to link directly to specific "pages" or features within an app.
For example, if you tap on a link to a specific product in the Amazon app, you‘ll be taken directly to that product page within the app, rather than to the Amazon app‘s homepage. Similarly, if you tap on a link to a specific Instagram post or TikTok video, you‘ll be deep linked directly to that content within the respective app.
Deep linking has become increasingly important as mobile users spend more and more time within apps rather than on the mobile web. According to data from App Annie, mobile users spent an average of 4.2 hours per day using apps in 2020, up 20% from 2019. And in Q1 2021, a record 9.2 billion apps were downloaded globally across the App Store and Google Play.
As users spend more time in apps, it‘s crucial for developers and marketers to be able to direct them to the right content at the right time. Deep linking makes this possible by creating connections between apps and allowing for more targeted and efficient user journeys.
How Deep Linking Works
So how exactly does deep linking work on a technical level? It all starts with URL schemes.
Just like "https://" is the URL scheme for secure websites, apps can define their own custom URL schemes to enable deep linking. For example, the URL scheme for Twitter‘s iOS app is "twitter://", while the scheme for the Yelp app is "yelp://".
Here‘s an example of what a deep link using a custom URL scheme might look like:
twitter://user?screen_name=elonmusk
This link would open the Twitter app and take the user directly to Elon Musk‘s profile page.
However, custom URL schemes have some limitations. They only work if the user already has the app installed on their device. If they don‘t have the app, tapping the link won‘t do anything. Additionally, custom URL schemes don‘t provide any fallback options for routing users to the right content if the app isn‘t installed.
To address these issues, Apple introduced Universal Links in iOS 9, and Google introduced App Links (also known as Android App Links) shortly after. These deep linking standards allow developers to associate their apps with a website domain, enabling links to that domain to open directly in the app if it‘s installed, or in a web browser if not.
Here‘s an example of what a Universal Link might look like:
https://www.example.com/product/123
If the user has an app installed that has registered the "example.com" domain as a Universal Link, tapping this link will open the app and take the user directly to the product page for product 123. If the user doesn‘t have the app installed, the link will open in their default web browser instead.
To implement Universal Links, developers need to upload an "apple-app-site-association" file to their website that specifies which URLs should open in the app. They also need to configure their app to register the associated domains. Similarly, App Links on Android use an "assetlinks.json" file for verification.
One advantage of Universal Links and App Links is that they allow for more graceful fallbacks when the app isn‘t installed. They also provide better security than custom URL schemes, as they require the app to prove its association with the website domain.
However, implementing Universal Links and App Links requires more development work than simple custom URL schemes. They also don‘t work for all types of links, such as links shared on social media or messaging apps.
As a result, many apps use a combination of custom URL schemes and Universal Links/App Links to enable deep linking. The choice often depends on the specific use case and the trade-offs between compatibility, security, and ease of implementation.
The Trust Wallet Deep Linking Controversy
One area where deep linking has proven particularly important is in the world of cryptocurrency and decentralized apps (dApps). Many popular crypto wallets, such as Trust Wallet, MetaMask, and Coinbase Wallet, have used deep linking to enable users to easily connect to dApps and decentralized exchanges (DEXes) to trade tokens and interact with blockchain-based services.
However, in June 2022, iOS users of Trust Wallet found that deep linking to dApps no longer worked after updating to version 6.0 of the app. Instead, they were greeted with an error message stating "Deep link is not supported". This caused confusion and frustration for many users who had come to rely on the convenience of accessing dApps directly through the Trust Wallet app.
The root cause of the issue was a change in Apple‘s App Store Review Guidelines. Specifically, Apple introduced a new guideline, 4.7, that states "Apps using background services must use the appropriate background task for the job." This meant that Trust Wallet could no longer run its dApp browser continuously in the background, which was necessary for enabling deep linking to dApps.
As a result, Trust Wallet was forced to disable the dApp browser feature entirely on iOS in order to comply with the new guideline and avoid being removed from the App Store. Android users were unaffected, as Google does not have a similar policy for background tasks.
The change highlights the challenges that crypto apps face in navigating the sometimes restrictive policies of mobile app stores. While Apple‘s guideline was intended to improve battery life and performance for users, it had the unintended consequence of breaking a key feature for many crypto users.
It also underscores the importance of decentralization and Web3 principles. Many in the crypto community argue that relying on centralized platforms like the App Store ultimately harms innovation and limits user freedom. In an ideal Web3 world, users would be able to access dApps and services without intermediaries dictating what is and isn‘t allowed.
That said, the Trust Wallet team has indicated that they are working on alternative solutions to re-enable dApp functionality on iOS in a way that complies with Apple‘s guidelines. One possible approach is to use WalletConnect, an open-source protocol that enables connections between wallets and dApps using QR codes or deep links.
Deep Linking and Mobile Marketing Attribution
Beyond its applications in crypto, deep linking has also become a crucial tool for mobile marketers looking to optimize their campaigns and track their return on investment (ROI).
One of the key challenges in mobile marketing is attribution – that is, determining which campaigns, channels, and creatives are driving app installs and user engagement. Deep linking makes it possible to track user journeys from ad clicks to app opens and even to specific in-app events or purchases.
Here‘s a simplified example of how mobile attribution with deep linking might work:
A user clicks on an ad for a mobile game on Facebook. The ad‘s URL contains a unique identifier for the specific campaign and ad creative.
If the user doesn‘t have the game installed, they are taken to the App Store and prompted to download it. The unique identifier is passed along to the App Store URL.
Once the user installs and opens the app, the identifier is recognized by the app‘s mobile measurement partner (MMP) SDK. The SDK attributes the install to the specific Facebook campaign and ad creative.
As the user continues to engage with the app, the MMP can use deep links to track their journey and attribute downstream events like level completions or in-app purchases back to the original campaign.
This level of granular attribution data allows marketers to optimize their campaigns in real-time, allocating budgets to the channels and creatives that are delivering the best results. It also enables more personalized and targeted user experiences, as marketers can deep link new users directly to customized onboarding flows or specific content based on the campaign they came from.
According to a report from AppsFlyer, a leading mobile attribution and marketing analytics platform, apps that used deep linking in their install campaigns saw 2.1x higher retention rates and 9.5% more revenue per user than apps that didn‘t use deep links. The report also found that deep linking improved in-app engagement rates by 8.5%.
| Campaign Type | Retention Rate Improvement | Revenue Per User Improvement |
|---|---|---|
| Install Campaigns | 2.1x | 9.5% |
| Engagement Campaigns | 8.5% | – |
Source: AppsFlyer, "The State of Mobile App Retention 2020"
Of course, implementing effective deep linking for attribution is not without its challenges. Marketers need to ensure that their deep links are properly configured and that they are using reliable attribution partners that can provide accurate and actionable data.
There are also ongoing concerns around user privacy and data protection. As Apple‘s iOS 14 update introduces new restrictions on user tracking, marketers may need to find alternative ways to attribute campaigns and measure ROI that rely less on individual-level data.
The Future of Deep Linking
As the mobile app ecosystem continues to evolve, it‘s likely that deep linking will play an increasingly important role in enabling seamless user experiences and facilitating connections between apps and services.
One area where deep linking could have a major impact is in the world of augmented reality (AR) and virtual worlds. As more brands and developers create AR content and experiences, deep links could allow users to easily jump between different AR apps and assets. Imagine being able to tap on a deep link in a shopping app to try on a virtual pair of sneakers, then seamlessly jump to a social media app to share a photo of yourself wearing them with your friends.
Deep linking could also be crucial for the growth of the decentralized web and Web3 applications. Just as deep links allow for easy navigation between siloed mobile apps, they could enable users to move between different dApps and decentralized services without friction. Imagine being able to go from a DeFi lending protocol to an NFT marketplace to a decentralized social network with just a few taps, all while maintaining control over your identity and data.
However, realizing this vision will require standardization and collaboration across the industry. Developers will need to agree on common deep linking protocols and best practices, and ensure that their implementations are secure and privacy-preserving.
There is also a need for better education and awareness around deep linking, both for developers and end-users. Many app users may not even be aware that deep linking exists, or understand how it can be used to enhance their mobile experiences. By providing clear and transparent information about deep linking and its benefits, the industry can drive greater adoption and unlock new use cases.
Ultimately, the power of deep linking lies in its ability to break down the barriers between apps and create a more open, interconnected mobile ecosystem. As we move towards a world where our digital and physical lives are increasingly intertwined, deep linking will be an essential tool for navigating the complex web of apps, services, and experiences that make up our daily lives.
Conclusion
Deep linking is a powerful technology that has already transformed the way we interact with mobile apps and services. By enabling direct links to specific content and features within apps, deep linking has made it easier for users to discover and engage with the things they care about, while also providing new opportunities for developers and marketers to drive growth and measure success.
However, as the Trust Wallet controversy on iOS demonstrates, the world of deep linking is not without its challenges and limitations. Developers must navigate a complex landscape of different standards, platforms, and policies, while also ensuring that their implementations are secure, privacy-preserving, and user-friendly.
As we look to the future, it‘s clear that deep linking will only become more important as our lives become more digitally intertwined. From enabling seamless AR experiences to powering the decentralized web, deep linking has the potential to unlock new frontiers of innovation and creativity in the mobile app ecosystem.
But realizing this potential will require ongoing collaboration, standardization, and education across the industry. Only by working together can we create a more open, interconnected, and user-centric mobile future – one where deep links are not just a tool for developers and marketers, but an intuitive and essential part of how we all navigate the digital world.
