Our project currently uses a value called k_uuid as the unique identifier for each user. This value is generated based on the Identifier for Vendor (IDFV) and is stored both in the Keychain and local storage to prevent changes when the app is uninstalled and reinstalled.
However, we are now facing a critical issue. We plan to transfer the app from Developer Account A to Developer Account B using Apple’s App Transfer Process. During this transfer:
Our backend services will remain unchanged
Our development team will remain the same
Only the developer account will change
We understand that during this transfer process, the Team ID associated with the developer account will change, which in turn will make it impossible to access the existing Keychain data. As a result, if a user uninstalls and reinstalls the app after the transfer, their original unique ID (k_uuid) will change. This will lead to serious consequences, including:
Inability to recognize returning users
Loss of user data such as subscriptions, virtual currency, and usage history
Therefore, we urgently request guidance and assistance from Apple to:
Ensure that the k_uuid remains unchanged after the app transfer, or
Provide a solution that allows us to map users between the old and new environment, ensuring data continuity and integrity for all existing users
IDFV is fundamentally brittle, which is why the docs say:
if your app stores the value of this property anywhere, you should gracefully handle situations where the identifier changes.
Your current recovery strategy relies on the fact that your app’s keychain items are preserved when the app is deleted. That’s an implementation detail, and thus not something you should be relying on. See my posts on this thread.
Provide a solution that allows us to map users between the old and new environment, ensuring data continuity and integrity for all existing users
I think it’s up to you to craft that solution. One path forward would be:
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Decide on a mechanism to identify your users. You could create your own account system, adopt Sign in with Apple, or whatever.
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Ship a version of your app from your old team that migrates the user to that system.
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Once an appropriate fraction of your users have run that version of your app, transfer the app to the new team.
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"