Hello,
We have three apps (App A, App B, and App C), all of which use Sign in with Apple. Currently, all three apps are under our company’s developer account (Team A). When users sign in to any of these apps, they receive the same user identifier (sub), allowing us to share user information across apps.
ASAuthorizationAppleIDCredential *appleIDCredential = authorization.credential;
NSString *user = appleIDCredential.user;
We are now planning to transfer one of these apps (App A) to another company’s developer account (Team B). According to Apple’s documentation, I understand that there is a 60‑day migration window after the App Transfer completes, during which we can use the /auth/usermigrationinfo endpoint to migrate user data.
My specific questions are as follows:
During the 60‑day window, if users with the same Apple ID sign in to App A (now transferred to Team B) and App B/App C (still under Team A), can we use the /auth/usermigrationinfo endpoint to link the new sub (belonging to Team B) for App A with the old sub (belonging to Team A) for App B and App C, thereby enabling cross‑app user identification?
After the 60‑day window expires, the /auth/usermigrationinfo endpoint will no longer be available. If App B and App C have not yet been transferred by that time, will the same user signing in to App A (Team B) and App B/C (Team A) be treated by Apple as two completely different users, making it impossible to achieve account information interoperability?
Based on the above, to ensure that user data across all apps can ultimately be interoperable, must we complete the transfer of all apps within the 60‑day window? Or, is it necessary to generate and save transfer_sub for all potentially affected users in advance during these 60 days, so that we can use them later?
We look forward to your reply. Thank you.