Universal Links

Universal Links are ordinary https:// URLs that iOS routes to your app instead of Safari, once Apple has verified that you control both the domain and the app. They are the iOS half of public deep linking; the Android equivalent is Android App Links.

Verification needs two pieces that point at each other:

• An Associated Domains entitlement in the app, such as applinks:example.com. In Expo this is ios.associatedDomains in the app config.
• An apple-app-site-association (AASA) file on the domain at /.well-known/apple-app-site-association, served over HTTPS with no redirects and a JSON content type, with no .json extension.

{
  "applinks": {
    "details": [{ "appIDs": ["ABCDE12345.com.example.app"], "components": [{ "/": "/post/*" }] }]
  }
}

The app ID is your Team ID followed by the bundle identifier. A typo in either fails silently.

Once the link reaches the app, React Native handles it like any other deep link, through the same navigation linking config.

The gotchas that make Universal Links feel broken when they are not:

• Apple caches the AASA file through its own CDN, so a fixed file can take a while to be picked up. Changes are not instant.
• Typing or pasting the URL into Safari’s address bar does not open the app. Neither does tapping a link to the same domain while already on that site. Test from Notes or Messages.
• If the user long-presses and chooses to open in Safari, iOS remembers that choice for the domain.
• A wildcard path that also matches your login or password-reset pages will hijack them into the app.

Keep a working web page at every linked path: users without the app installed will land there.