I'm experiencing an issue where the App Group shared container appears to be recreated (with a new creation date) during an app update, resulting in complete loss of locally stored data. Background My app uses UserDefaults, Realm, Core Data, and CloudKit, with all local data stored in the App Group container (FileManager.containerURL(forSecurityApplicationGroupIdentifier:)). The app has been available since 2016 and has a stable user base. Starting last year, I began receiving occasional reports from users saying all their data in the app had disappeared. To investigate, I added diagnostic logging that detects when an existing user's data appears to have been reset — specifically by checking the App Group container's file system creation date, and the existence and values of expected files. What the diagnostics revealed When the issue occurs, I observe the following: The App Group container has a recent creation date, far newer than the u
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