OneLink™ 2/4: Sending existing users to open your app

There are three technologies available to open the app directly after a click:

• iOS Universal Links: Works with iOS 9 and up, and provides a smooth, secure experience when opening your app. 
• Android App Links: Works with Android 6 and up, and provides a smooth, secure experience when opening your app. 
• URI schemes: 
  • URI schemes are one of the oldest and most common ways of opening an app from a link. 
  • A URI scheme is an address, that when accessed, opens your app if it's installed. They are similar to website links, but open apps instead of websites.
  • The URI scheme must be the same for iOS and Android, but they are set up differently. 
  • They are an effective fallback method for when Universal or App Links don't work. Also, it's the only way to open your app from a link on a device with below Android 6 or below iOS 9.

For the best user experience, security, and device coverage, we recommend enabling as many technologies as possible. If you enable all link technologies, OneLink will automatically apply the best method for each user. 

To update the OneLink template:

1. In the AppsFlyer dashboard, go to Engagement & deep linking > OneLink Custom Links.
2. Hover over the OneLink template you created using the previous guide and click the Pen icon to edit the OneLink template.
   
3. Click the Redirecting & deep linking tab.
4. Scroll down to When app is installed.

   

5. Follow the instructions for iOS, Android, and fallback setup:
   
   iOS Universal Links Android App Links URI scheme

   Universal Links take the format of regular web links (e.g. https://yourbrand.onelink.me or https://www.yourbrand.com) and thus require setting a subdomain (covered in the previous guide). OneLink also supports fully branded domains, but that isn't necessary to complete this guide.

   To launch the app using Universal Links:

   1. Contact your iOS developer:
      • Give them the subdomain for this OneLink template.
      • Tell them to follow these instructions.
      • The developer returns to you with the Team ID (also called Apple App ID Prefix, e.g., PF23MIWNTW).
      • If the app is not yet published, the developer must also give you the Bundle Identifier (e.g., com.myapp.something).
   2. In the OneLink template page click Change to launch the app using Universal Links.
   3. In the new window, select Launch the app using Universal Links.
   4. In the Team ID field, enter the team ID provided by the developer.
   5. If the app is not published, also enter the Bundle Identifier.
   6. Click Save changes.

   App Links take the format of regular web links (e.g. https://yourbrand.onelink.me or https://www.yourbrand.com) and thus require setting a subdomain (covered in the previous guide). OneLink also supports fully branded domains, but that isn't necessary to complete this guide.

   Before you begin:

   Record the subdomain you chose for this OneLink template.

   To launch the app using Android App Links:

   1. Contact your Android developer: 
      Tell them to generate a SHA256 fingerprint by following these instructions.
      The developer will come back to you with the SHA256 fingerprint. For example:    DC:65:43:67:F3:BD:02:52:AC:B4:50:F1:74:54: 23:49:4D:49:6C:E6:DF:56:BD:CB:53:06:11:5B:C9:4E:5D:0C
   2. In the OneLink template page click Change to launch the app using App Links.
   3. In the new window, select Launch the app using App Links.
   4. In the SHA256 fingerprint field, enter the SHA256 fingerprint provided by the developer.
      An auto-generated intent-filter code appears.
   5. Contact your Android developer: 
      Give them the auto-generated intent-filter code.
      Tell them to follow these instructions and confirm completion.

   The URI scheme mainly serves as a fallback for both iOS and Android users, and so must be the same at both.

   To set the Android and iOS URI fallback:

   1. Contact your iOS AND Android developers and decide on a URI scheme. For example: feedmeapp://
      

       Tip

      Use a URI scheme that is as unique as possible to your app and brand to avoid coincidental overlap with other apps in the ecosystem. Overlap with other apps is an inherent issue in the nature of URI scheme protocol.

      The URI scheme should not start with http or https.

   2. Tell the iOS developer to implement the URI scheme in their app by following these instructions.
      AND
      Tell the Android developer to implement the URI scheme in their app by following these instructions.
   3. When done, the developer confirms the value of the URI scheme implemented. Expect it to look like: exampleapp:// or exampleapp://home or exampleapp://main, etc.
   4. In the OneLink template page click Add URI scheme to launch the app.
   5. Select Launch the app using URI scheme.
   6. Enter the URI scheme value.
   7. Click Save changes.
   8. Test the URI scheme (this can be done by you OR your developers):
      1. Go to this free public testing tool on both an iOS and an Android device that has your app installed.
      2. Tap the link generated by the tool.
         If the URI scheme is correct, the app opens.
6. Click Update OneLink template.

After updating the OneLink template, the custom attribution link (created using the previous guide) can be used to retarget and correctly attribute users with the app installed. When these users click the link, the app opens on their devices. 

It is important to mark campaigns for existing users as retargeting campaigns. This enables you to see the re-engagements performed by users clicking on your custom link.

Existing users that click on non-retargeting links (UA) also launch the app, and have the same user experience. However, their re-engagements are recorded as regular sessions, which means it's impossible to measure the success of the owned media campaign.

To enable retargeting on the custom link:

1. In the AppsFlyer dashboard, go to Engagement & deep linking > OneLink Custom Links.
2. Click the selected OneLink template.
3. From the list, select the Custom link you created in the previous guide. 
4. In the Attribution section, activate Retargeting campaign.
5. Click Update link.

If Retargeting was never enabled for the app, you need to do it once (learn more).

To set Retargeting at the app level:

1. In the AppsFlyer dashboard, go to Configuration > App Settings.
2. In the Attribution section, enable Retargeting campaign measurement.
3. Click Save settings.

If your custom link is not intended for social media apps, you can skip directly to testing.  

Social media apps may break the smooth experience of existing users using Universal Links or Android App Links. This can be overcome by creating a social media apps landing page. Users who click ads in social media apps are then redirected to an AppsFlyer-generated landing page. From there, they can be deep linked, or continue to install the app.

AppsFlyer provides a variety of social media apps landing page templates. Element positions in the templates are fixed, but the elements themselves are customizable, including background image or color, titles, texts, images, buttons, tags, and more.

The social media app landing page can be used with the following social media apps:

• Instagram
• Facebook
• Pinterest for iOS
• Snapchat
• Twitter
• WeChat

User experience

When the user engages with the CTA button in the landing page:

• If app is installed: the clicking user launches the app.
• If app is NOT installed: the user is taken to the relevant app store. Upon install, it's possible to defer deep link the user (explained in OneLink 4/4).

To use the social app landing page: 

1. Configure the landing page as described in the following section. 
2. To fully support deep linking on both iOS and Android, make sure the URI fallback is configured for the custom link. Also, add af_force_deeplink=true to the attribution link.
3. Record the generated OneLink short URL.
   The social media apps landing page does not work with long OneLink URLs.
4. Post the OneLink short URL on the social app.

Attribution is determined based on your attribution settings.

To set up the Social apps landing page:

1. In your Custom link setup, click the Social apps landing page tab.
   

   

2. Click Create landing page.
   A window to choose a landing page template opens.
3. To choose a landing page template, hover over the selected template and click Create.
   Tip: hover over the  icon of a template to see in which cases it should be used.
4. Customize all the elements in the landing page creative. To do so, select elements by name or click on them on the preview image.  
   Tip: Save your texts in case you replace the creative template.
5. Replace all template images with your own images.
   
   • Enter image URLs including the extension, e.g. https://example.com/image.png.
   • Use one of the following file types: jpeg, jpg, png. 
     Note: webp format is not supported. 
   • The recommendations for the images are:
     
     

     Template image type	Maximum image file size	DPI	Image ratio
     Collection	300 KB	72	16:9 (horizontal)
     Trapeze/carousel	300 KB	72	1:1
     Flyer/poster/blurry poster	300 KB	72	9:16 (vertical)

   • If one or more of the images isn't an exact URL, an error will display, and you will not be able to review the creative.
     
     

     

6. To review the landing page creative, click Review.
   If changes are needed, click Back to editor.
   
   

   

7. To save your landing page, click Done.
   Important: New/updated landing page creatives only apply after generating/updating the custom link.

Prerequisites:

An Android and/or iOS device with the app installed. Make sure it is the app source and version where the developer(s) made changes (and implemented Universal Links, App Links, and/or URI schemes).

To test your link:

1. In the AppsFlyer dashboard, go to Engagement & deep linking > OneLink Custom Links.
2. Click the selected OneLink template.
3. From the list, select the Custom link.
4. Hover over the Actions icon of the link you want to test and click Get URL. 
5. Send the short or long URL to your phone. You can either:
   • Scan the QR code with your phone camera or QR scanner app.
   • Email or WhatsApp yourself the link, and open it on your phone.
     Note: Do not paste into iOS notes, or directly into a mobile browser. Often, the mobile operating system intentionally will not open the app in this context.
6. Click the link on your mobile device.
   The app should open to its home screen.
   
7. Go to the AppsFlyer Retargeting dashboard.
   Look for a new click/re-engagement (app open) under your link's media source (e.g. test) and the campaign name you put in the URL.