iOS Associated Domains (Universal Links) with Wildcards not working

ios ios-universal-links associated-domains
Bocaxica picture Bocaxica · May 18, 2016 · Viewed 8.7k times · Source

In an iOS app I am working on I have setup Associated Domains (Universal Links). The app hosts multiple domains. Some domains I have set up with a wildcard. These domains do not seem to work. For example, I want to link to https://news.mydomain.com/. If I add the following to the list of associated domains:

applinks:*.mydomain.com -> Does not work

applinks:news.mydomain.com -> works fine

So I believe I did set up all correct, the apple-app-site-association file is setup fine. I can even see in both cases (using Charles Proxy) the apple-app-site-association file got retrieved ok.

In the case of the wildcard, the link only opens in Safari.

When I configure the domain without a wildcard, the App opens.

Am I missing something here? I am running iOS 9.3.2 on the device and I am running Xcode 7.3.1 which are today the latest versions.

Answer

focorner picture focorner · Nov 7, 2016

I added my findings to this thread: https://forums.developer.apple.com/thread/47315

In short, even in iOS 10, it appears that the wildcard setup requires that the apple-app-site-association file be served by the wildcard's root.

For instance, if you want to use *.domain.com, then the apple-app-site-association needs to be hosted at both, e.g., app1.domain.com and domain.com, else it won't work with simply specifying applinks:*.domain.com in Xcode.

This is unfortunate if your main site is hosted at www.domain.com, and that you have a 301 redirect on domain.com (which redirects you to www.domain.com), because Universal Links do not allow redirects.

The workaround I found was to create a main subdomain for your app, and to use sub-subdomains for the wildcard. E.g.

  • app.domain.com (must serve the apple-app-site-association file)
  • server1.app.domain.com (must serve the apple-app-site-association)
  • server2.app.domain.com (...)

That way, in Xcode, you may only specify applinks:*.app.domain.com and Universal Links will work without you having to specify server1.app.domain.com, server2.app.domain.com, and so on... in Xcode.

Note, however, that you must also explicitly specify applinks:app.domain.com if you plan on using that server as well with your app.

I hope this helps.

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