Universal Links and Deep Links: What's the difference?

James Haslam

Feb 5, 2019

Universal links and deep linking are the talk of the industry, brought up as a complex and ongoing challenge that both app users and developers face. As a deep linking solutions provider we wanted to give some insight into the nature of universal links, and what differentiates them from the title of just ‘iOS deep links.’

What are ‘Universal Links’?

Universal links are Apple’s way of launching apps on their operating system from a website, also known as a web view. They link to content inside an app or website, giving iOS users an integrated mobile experience.

Broadly, there aren’t many differences between universal links and traditional deep links. However, universal links are exclusive to Apple devices, and have the ability to open a web page from an application.

In order to get a better understanding of how universal links and deep links differ, let’s take a look at how they work.

How Universal Links work

The implementation of universal links is similar to a standard deep link. However, instead of defining a custom URL scheme, a universal link matches a set of web pages to locations in-app. This means that when a user opens a web page which is matched as described, iOS automatically redirects the user to the app.

Universal links are available in iOS version 9 and above, and work even when the app isn’t installed on a user’s device. When tapping a link to your website without the app installed, the user will then be linked to your website in Safari. So, both your website and your app work for one URL.

Because Universal Links can lead users directly to your app when tapping links to your website, this method can increase app engagement and simplify the user experience.

Why do Apple’s universal links exist when deep links already do the job?

It was solely Apple’s decision to introduce universal deep linking to the mobile industry. The company’s developer page suggests that they wanted to provide greater security, privacy and flexibility. It may also have something to do with Apple wanting to own the experience, coupled with creating a more reliable system for iOS. Whatever the reason, Apple now owns and shapes a part of the deep linking ecosystem for a significant proportion of users.

Are there any problems that universal links created?

There are various technical restrictions when it comes to universal linking, from ‘the right corner evil’ to broken links that you should be aware of. Let’s take you through some of the ones that many come across:

The right corner evil

The right corner evil refers to the ‘breadcrumb’ in the top right of an iPhone or iPad, clicked on if a user wants to move from app to web view and back again.

When a user clicks on a universal link iOS looks at the user’s recent choices to determine whether to open an app or a web page. If the user has tapped a universal link to your app, and then opened your site in Safari by tapping the breadcrumb button, iOS will remember that choice, and continue to open the site in Safari, even if the user wants to go back to the app.

This means that the user is essentially stuck in web view by mistake. iOS won’t re-open the app unless the user knows to tap in the Smart App Banner on the web page, and this can’t be reversed on the developer side. It’s up to the user to navigate through a banner, or press and hold until options open on the link, selecting ‘Open in App’.

Some users could then believe the app is somehow broken, whereas it’s the deep linking experience which is preventing them from accessing the application they want.

Broken links

Apps are continually updated to reduce size, release features, and to improve the experience. In some cases, a deep link in version 1 works fine, but in a new version the app and the in-app web view behave differently. This can change based on which version is installed - one link might work correctly, in other versions it may not. While Adjust can react to this, relying solely on universal linking could make the issue bigger.

This is another potential negative user experience that’s associated with the apps, not the OS. As with the right corner evil, developers and product managers could receive the blame for Apple’s implementation. Finding another solution with Adjust could help cut out the headaches.

Clicks stopping user flow in web view

There can be a couple of breaks that occur in Universal Linking:

  1. If the web view doesn’t support universal linking, or scheme based deeplinking, Adjust can’t deep link back into the application.
  2. As noted here ‘if you instantiate a SFSafariViewController, WKWebView, or UIWebView object to handle a universal link, iOS opens your website in Safari instead of opening your app.’ This means that even if a web view supports universal linking, but a click outside of the web view triggers initialization of the web view, universal links will not work.

In real terms, this breaks a user’s journey, potentially decreasing retention, and annoying your audience.

Is there a difference between Adjust’s deep links and Apple’s universal links?

While our deep linking service works cross-platform, we have integrated universal linking in order to include its functionality. While it is possible to use a single deep link per platform, the typical solution is to use the respective type of deep link on their separate platforms - and we’ve worked hard to ensure we support both.

What if I need more support when implementing universal links?

If you’re setting up for the first time, our documentation can help guide you through the process. However, our support team also has a wealth of knowledge and expertise on the issue of deep links, universal links, and more. Be confident that if you can’t find it in writing, our team will be able to help.

If you found this post useful, you may also be interested in how to create a deep link, and how deep linking works. Adjust’s deep link guide also gives you great insight into exactly what they are, how they work, and what they can do to improve your app experience. Download it today!

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