Starting with iOS 10.3, Apple introduced a new security feature which redirects clicks on mobile tracking links to Safari, and then prompts the user with a dialogue to proceed to the app store:
(Alternately, if the app is already installed on the user's device, and universal links is set up for the app - the user is deep linked into the installed app.)
If the user clicks Cancel, they stay on this blank page in Safari. To overcome this broken user experience, AppsFlyer tracking links have been enhanced to handle clicks on iOS 10.3 and above.
Regular Tracking Links
In the App Settings page, you can define a URL for iOS 10.3 fallback.
Any clicks on regular app specific tracking links (starting with https://app.appsflyer.com/) fallback to this URL if the iOS 10.3 user clicks on Cancel.
Note - this 10.3 redirect fallback can be configured only by account owners.
OneLink Tracking Links
Clicks on OneLink-based tracking links have their own fallback, which overcomes the iOS 10.3 redirect fallback URL. After clicking OneLink and clicking Cancel on the iOS dialog, the user is redirected to the Website URL defined in the OneLink’s configuration:
Special Tracking Link Parameter
If you want to explicitly define a fallback URL for a tracking link, you can use the af_ios_fallback parameter.
Here too, if the user clicks Cancel, the af_ios_fallback parameter value is used as fallback.
This parameter can also be used in OneLink tracking links, overriding the default URL defined in the OneLink Configuration.
What if no fallback is defined?
In this case, when a user clicks Cancel the following fallback page is displayed:
From this page the user can proceed to the app store.