uniqueidentifier - iOS: TestFlight beta app get new advertising identifier in each run

Question

I am getting new advertising identifier each time I run a beta app uploaded to TestFlight in iTunesConnect. Is it a normal behaviour? Will it happen for AppStore app too? I am using the Advertising Identifier to identify users and his credentials in some context. But if it changes in every run, the user have to activate in each run.

[[[ASIdentifierManager sharedManager] advertisingIdentifier] UUIDString];

In testflight build, in 3 runs, I got, e.g.

ID: 3E841B61-B007-44D3-B654-6C857122301E
ID: 2EC3682A-D162-4CE6-B07A-8B73282456A4
ID: 1D8513EA-0757-4E5F-8CEE-B6C4F782E966

This does not happen in debug or ad hoc builds. Can anybody shed some light on it?

Thanks in advance.

Answer 1

It is by design. It started happening in 2014. It will only happen in a TestFlight app, not in a production app in the app store. It's unfortunate--it makes it hard to test some apps realistically with actual beta testers.

In the WWDC 2014 talk, "User Privacy in iOS and OS X," by David Stites and Katie Skinner, they mention this. (This link only works in Safari.) You can see it in slide #8 of their slide deck.

In this transcript of the talk, you'll find: "Also this year, for TestFlight apps the advertising identifier will be different each time you call the API."