iOS Universal Links are not opening in-app

Question

So I followed this tutorial exactly and use the same values as the ones provided: https://blog.branch.io/how-to-setup-universal-links-to-deep-link-on-apple-ios-9

The Apple Association file is also ready in the link directory:
WEB_PAGE:PORT_NUMBER/apple-app-site-association

Everything seems to be set up on this side.

I've added the entitlements, updated the provisioning profile, and everything's set up.

When I run the app on my device, and open the link http://WEB_PAGE:PORT_NUMBER, this always opens Safari.

I even have breakpoints in the following method:

- (BOOL)application:(UIApplication *)application continueUserActivity:(NSUserActivity *)userActivity restorationHandler:(void(^)(NSArray * __nullable restorableObjects))restorationHandler

But zilch.

Has anyone perfected this? Is there something I'm missing?

Answer 1

There are a few possible issues.

1. Try pasting your domain into this link validator and make sure there are no issues: https://limitless-sierra-4673.herokuapp.com/ (credit to ShortStuffSushi -- see repo)

2. iOS logs an error message in the system logs if you don't have TLS set up properly on the domain specified in your entitlements. It's buried in the OS logs, not application logs. The error message will look like Sep 21 14:27:01 Derricks-iPhone swcd[2044] <Notice>: 2015-09-21 02:27:01.878907 PM [SWC] ### Rejecting URL 'https://examplecustomdomain.com/apple-app-site-association' for auth method 'NSURLAuthenticationMethodServerTrust': -6754/0xFFFFE59E kAuthenticationErr. Error message pulled from here, quick (incomplete) instructions on using CloudFlare for TLS here.

3. In my personal testing, clicking/typing in a link in Safari has never once opened the app directly. Clicking from other apps (iMessage, Mail, Slack, etc.) has worked. Others have reported that clicking links in Google search results have opened the app directly.

4. Note that if a Universal Link succeeds in opening your app and then you click through to Safari (by tapping your site in the top right corner of the nav bar in app), then iOS stops opening the app when you visit that URL. Then in Safari, you can pull down to reveal a banner at the top of the page with "Open". I wasted a lot of time on this. Note that clicking through to the site => disabling UL seems path specific, based on the paths you specify in the apple-app-site-assocation file. So if you have separate routes, yoursite.com/a/* and yoursite.com/b/*, if you click yoursite.com/a/* and it opens your app directly, you then have the option in the top right corner of the app to click through to yoursite.com/a/*. If you do that, subsequent visits to yoursite.com/a/* will open in browser, not app. However, yoursite.com/b/* should be unaffected and still open your app directly.

Let me know if you discover what the issue is. I'm personally very curious about how Universal Links work and what edge cases exist.

Answer 2

There are a lot of ways this can go wrong. Two points caused me trouble:

• In Xcode, when you add the Associated Domains entitlement, each entry needs to start with applinks: and then your domain name. E.g. applinks:www.apple.com.

• Though Xcode created an entitlements file for me, it did not include in my build: I had to click that box manually.

And yes, after doing that, it wasn't necessary to sign the apple-app-site-association file: it is just plain text, and it works, as long as it's served over HTTPS. (You'll still need to sign it if you're supporting iOS 8, though.)

Answer 3

To help debugging this issue, search for "swcd" in your device's console output when installing your app to see if registering your universal link worked or failed.

1. Use an actual device, not the simulator.
2. Delete the app from you device.
3. Connect the device to your computer, and view the device's console output in xcode. (window -> devices -> [your device] -> open console). Keep this window open.
4. Install your app and let it launch.
5. Filter the console output to "swcd". If it's sucessful you will see something like the folowing screenshot. If it fails you'll see something else. If you don't see anything then you messed something fundamental like adding the Associated Domains entitlement.

Answer 4

There is apparently an error in the documentation for making the association file for Universal Links.

Where it says:

The value of the appID key is the app’s team ID and the bundle ID

it should say

The value of the appID key is the app’s Prefix and the bundle ID

For most apps, it seems that the Team ID and app prefixes are the same, but if your app has been in the store for many years, these values can be different.

To find this value, open the Member Center on https://developer.apple.com and look at "Certificates, Identifiers & Profiles", click "Identifiers", then "App IDs" in the table under "Identifiers". Find your app, and use the Prefix value and Bundle ID there to create your AppID for the association file.

Answer 5

St.derrick's Answer is informative.

But to enable universal links again to open in app instead of safari we need to do the following thing.

• Long press on Universal link in Mail or iMessage, then you will see options whether to open in safari or in App.

Answer 6

To validate apple-app-site-association on the server side, you can use Apple's official validator.

https://search.developer.apple.com/appsearch-validation-tool/

Answer 7

It's also super important to increment the project version or build number after integrating universal links. Even if you delete/reinstall, iOS won't pickup the links unless you bump the version.

Answer 8

I realized that be problem for me was that links to the root directory a (eg. http://example.com/) did not open my app but if I added a path (eg. http://example.com/mypath) it worked. Adding "/" to the paths list sovled it:

{
    "applinks": {
        "apps": [],
        "details": [
            {
                "appID": "TEAM_ID.BundleIdentifier",
                "paths": [ "*", "/" ]
            }
        ]
    }
}

As answered by slutsker in this Apple Developer Forums thread.

Answer 9

For anyone who needs to easily test opening (Universal) Links, you can also open the link in your Simulator from the terminal with this command:

xcrun simctl openurl booted yourapp_or_http://yourlink

for example:

xcrun simctl openurl booted https://www.google.com

Answer 10

Quick steps to check whether you have implemented Universal Link correctly.

• Tap and hold on the link that you expect to launch the app. You should see a "Open in [your app name]" in the Context Menu.

• Open Notes app, type the link you expect to open the app. Tap Done. The link will turn yellow and tapping on the link should open your app, and not Safari.

• If the link http://yourDomain.com is not launching the app, try http://yourDomain.com/yourFolder/

• In Safari, If the Context Menu shows "Open in [your app name]" in safari, but tapping the link opens the link in safari itself instead of launching the app,

  a. Try pulling down on the safari page that opened when the link was clicked like the way you 'pull to refresh'. A banner should appear that can open your app. Tap the banner to open the app, close the app by pressing home button, get back to safari and try launching the app by tapping the link again. This time on, the app should get launched because tapping the banner should have saved the preference to open the link in app.

  b. If the app still don't get launched after the step a., try mailing the link to a webmail such as gmail and open the webmail site in safari and try clicking the link. If this works, you may have been trying to launch the app from the same domain as the link. From what I have seen, launching the app from the same domain mostly fails. Probably safari wont care to check whether the destination url is a universal link, when the link is into the same domain that user is on. So try to launch the app from another domain.

Answer 11

• Universal Links will not work if you paste the link into the browser URL field.

• Universal Links work with a user driven <a href="..."> element click across domains. Example: if there is a Universal Link on google.com pointing to bnc.lt, it will open the app.

• Universal Links will not work with a user driven <a href="..."> element click on the same domain. Example: if there is a Universal Link on google.com pointing to a different Universal Link on google.com, it will not open the app.

• Universal Links cannot be triggered via Javascript (in window.onload or via a .click() call on an <a> element), unless it is part of a user action.

source: https://dev.branch.io/getting-started/universal-app-links/support/ios/#appsbrowsers-that-support-universal-links

The 3rd bullet cost me about a day to figure out.

Answer 12

I have found 2 useful tools that you can use to debug issues with Universal Links:

1. On your phone, open the Settings app, select the Developer menu -> enable Association Domain Development and select Diagnostics. Insert the url that you have added to your entitlements file, and it will be validated:

2. The second one is mentioned in Apple's TN3155: Debugging universal links article. I recommend you read the full article, but especially the Host and verify your AASA chapter.

The mention using swcutil to verify your AASA files:

You can use these commands in Terminal by:

Running sudo swcutil dl -d <domain> to check that the AASA JSON can be downloaded successfully.

Running sudo swcutil verify -d <domain> -j <path-to-JSON> [-u <URL>] to check the contents of a downloaded .json AASA file. Verify that your domains match with -d and your URL path pattern matches with the JSON with -u. If both are successful, you will get a confirmation message.

For an app containing applinks:example.com and the AASA shown above, here is an example of using swcutil verify where “s” is the service, “a” is the App ID, and “d” is the domain:

% sudo swcutil verify -d example.com -j ./example.json -u https://example.com/test
{ s = applinks, a = ABCD123.com.example.app, d = example.com }:
Pattern "https://example.com/test" matched.

Since the pattern /test is included in the AASA, the JSON has successfully pattern matched and is verified. For the path /path/1, since it is set to be excluded in the AASA, you would see a message confirming the exclusion:

Pattern "https://example.com/path/1" blocked match.

Answer 13

Incase people here are looking for other solutions, we put together a whole step-by-step on debugging Universal Links as we've seen a lot of issues pop up, causing a LOT of headaches.

Check it out:

Universal Links Debugging Guide

If you're just looking to set up Universal Links fresh, this guide is really helpful:

iOS Deep Linking Setup Guide

Hope they're helpful!

Answer 14

Just thought I would add some things I discovered in case more people encounter the same issues as me in the future. These are mostly related to authentication errors.

Even though apple doesn't explicitly state it, the apple-app-site-association file must be served over https, even if signed. The certificate used for https must also be trusted by apple. So while a certificate added to the device in Settings -> General -> Profiles will allow https in safari, it will not allow universal links to work.

In the device logs, on an authentication error between the device and the server, there will be a value printed like "TrustResultValue" : 4. A TrustResultValue of 5 means the certificate is for the wrong domain (Eg. test.com served from www.test.com). A TrustResultValue of 4 means the certificate is not trusted for this use.

There may be some helpful steps for debugging here. The "Testing access to apple-app-site-association" section is a step by step guide for how to make sure the device is getting the apple-app-site-association file. The steps boil down to:

1. Uninstall the app. This is necessary because the file is downloaded on install.

2. Stop the server from properly serving apple-app-site-association.

3. In xcode, open Window -> Devices and then select your device.

4. Open the device logs by clicking the triangle at the bottom of the window.

5. Clear the logs by clicking the trashcan to clear any previous logs that might be related.

6. Reinstall the app with xcode by clicking the play button.

7. After the app has launched, if the device is correctly requesting the file then the device logs should contain an error that can be found by searching for "apple-app-site-association".

If the apple-app-site-association file is properly served (step 2 is left out) then there should be no error. An authentication error may instead be displayed if that is the problem.

Answer 15

We've added apple-app-site-association file to this location:

https://example.com/apple-app-site-association

On iOS 9 it worked fine, but on iOS 10 it didn't work.

It appeared that problem was with .well-known path:

https://example.com/.well-known/apple-app-site-association

Because of https://example.com/.well-known/apple-app-site-association path redirected to https://example.com

<Notice>: Allowing redirect 'https://example.com/.well-known/apple-app-site-association' -> 'https://example.com/'
<Notice>: ### Rejecting AASA file size 154466 for URL https://example.com/.well-known/apple-app-site-association

In my opinion if somehow .well-known path doesn't work correctly it breaks universal links.

Answer 16

The most common cause is when user tap on the top right, thus telling iOS to NOT open the app (in this case Uber) in the future.

To fix, pull down to reveal the smart banner and tap on OPEN:

This will subsequently "remember" to open the app.

Answer 17

For ios13, there is a new format - check out here https://developer.apple.com/documentation/safariservices/supporting_associated_domains_in_your_app?language=objc

I updated my file to look like this:

 {
  "applinks": {
    "apps": [],
    "details": [
        {
          "appIDs": ["1234.app.company.appname"],
          "appID": "1234.app.company.appname",
          "components": [
            {
              "/": "/login"
            }
         ],
           "paths": [ "/login" ]
        }
    ]
  },
  "webcredentials": {
    "apps": ["1234.app.company.appname"]
  }
}

Answer 18

Sometimes I find that everything is fine with the association file but iOS decides to always open the universal link in Safari. To test if the app recognises the app link I add the URL to Notes or a Calendar entry and then long press it so the contextual menu appears. If it says "Open in {YOUR APP}" then the link is working but iOS is deciding to open it in Safari. Tapping "Open in {YOUR APP}" will tell iOS to open valid universal links via your app from then on.

Answer 19

After spending a day trying to get this to work, Restarting my phone solved the problem.

Uninstalling/Reinstalling the app didn't work either.

Answer 20

I've managed to make it work, but it took quite some time and struggle. Note that unless you sign the apple-app-site-association file (signing is optional!) tapping on a link in Safari will not open your app (it has caused me a lot of headache).

Answer 21

After two days it turned out for me, that these kind of links (from branch)

applinks:xxxx.app.link

work only after Archiving (also Ad-hoc) the application and install it to the phone.

Answer 22

Took me close to a day to figure this out. The issue I had was not downloading the updated provisioning profiles in XCode (I also restarted XCode after this).

(Preferences > Accounts > View Details > Download All)

Answer 23

You can test universal links in simulator

From the App Search Programming Guide: Support Universal Links

Answer 24

Hope this helps someone because this took me about two days to figure out.

We had to add www. to our associated-domains in our .entitlements file.

        <string>applinks:www.yourdomain.com</string>
        <string>activitycontinuation:www.yourdomain.com</string>

Because if we used yourdomain.com instead of www.yourdomain.com our servers did a redirect -> 304 and then didn't include the content-type: application/json for the apple-app-site-association file.

N.B. the universal links still work for yourdomain.com and www.yourdomain.com

Answer 25

If you are hosting your apple-app-site-association on Firebase, make sure to put it in /.well-known/ subdirectory! It appears that Xcode queries that URL first, and if it succeeds, it makes no attempt to query the apple-app-site-association in the root directory. For some reason, firebase engineers made the hosted websites to automatically respond to /.well-known/apple-app-site-association with an empty (but correctly formed) association file that overrides your custom one, leaving you with no clue why nothing works!

Answer 26

In my case I needed to make the server serve the apple-app-site-association file using content type: application/pkcs7-mime. In nginx I did it using this approach:

location ~ /.well-known/apple-app-site-association {
         default_type application/pkcs7-mime;
 }

As other suggested I also had to make sure I:

• Use the new iOS apple-app-site-association format https://developer.apple.com/documentation/safariservices/supporting_associated_domains
• Use the correct TEAM ID so it becomes "appIDs": [ "TEAM_ID.my-app-bundle-id"],
• Make sure in Xcode's entitlements, the app associations start with applinks:

Note that I never saw the "success" messages in the Console app as shown in screenshots by another user. In the console I kept getting Entry [...] needs its JSON updated because the app PI changed, but this was not an issue.

Also note that when trying to open the apple-app-site-association in the browser, the file gets downloaded instead of displayed, but this was not an issue in my case.

And as always, use a real device, re-install app whenever you change things, potentially also restart device and maybe increment app version number.

Answer 27

In my case the encoding of the file was incorrect.

Make sure you encode the file using UTF-8 and that you specify it in the Content-Type header:

Content-Type: application/json; charset=utf-8

You can easily verify it by pasting your URL on this site:

• https://jsonformatter.curiousconcept.com/

Answer 28

Go to developer.apple.com and edit one of your distribution profiles. In the editing page you can open a pop up for App IDs that will show a list of your app names and in () round brackets behind the app's name it reveals all your real App IDs. Some apps might have your team ID as prefix but some do not. Make sure to use exactly what you see in that pop up menu inside the () and put it into the apple-app-site-association details appID field. I had exactly this issue with an app and its universal links.

Answer 29

The issue for me turned out to be the apple-app-site-association file. According to Apple's documentation, only the applinks parameter is required. I added the activitycontinuation parameter and it worked.

{
  "activitycontinuation": {
    "apps": [
      "9JA89QQLNQ.com.apple.wwdc"
    ]
  },
  "applinks": {
    "apps": [],
    "details": [{
        "appID": "9JA89QQLNQ.com.apple.wwdc",
        "paths": [ "/wwdc/news/", "/videos/wwdc/2015/*" ]
      }]
  }
}

Answer 30

Haven't really seen the exact same issue/solution combo that got it working for me so might as well add mine incase someone has the same problem!

For my app I am using a custom URL scheme (set in APP_TARGET > Info > URL Types) and set the URL scheme from here into the Firebase console to match but still wasn't working.

My problem was actually two problems:

Watch out if checking Automatically Manage Signing

If you are checking Xcode's "Automatically manage signing" setting like I was, since I was just trying to make a quick demo app, you will want to ensure that the TeamID that is used matches the one in your Firebase console. I originally went to my Apple Developer Account and copied the team ID from my Membership page, but later saw that the actual ID being used by Xcode was different. (You can find this in APP_TARGET > General > Signing > Signing Certificate. For me it looked like iPhone Developer: My Name (TEAM_ID)).

Prefix your TeamID to your Bundle Identifier in your URL Types

After I ensured these matched in my Firebase console and Xcode, my next problem was the identifier for my URL scheme. It's typical to use your bundle identifier here, but Firebase actually prefixes this with the Team ID you gave in your Firebase console, so I had to prefix it to the identifier in the URL types section in Xcode as well.

After these two fixes and re-downloading the GoogleService-Info.plist file I had no problem open up my dynamic links.