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Delete local iCloud Data on Device (e.g. at first app launch/reinstallation)

If a user installs an an app which uses iCloud with a UI(Managed)Document, then uses the app, creates data which is saved to iCloud and then deletes the app on his phone, the iCloud data will stay on the device (transaction logs etc.). If the user reinstalls the app it will try to use these old files.

I have the following two problems with that:

  • The iCloud documents could have changed in the meanwhile and there might be problems when the user has no network connection on the first launch after reinstalling the app.
  • The iCloud documents for this app could have been deleted by the user (via settings or in Mac OS Finder in the user library). Now, when the user has no network on the first launch after reinstalling the app, the app might think that there is an ubiquity container with data even though it's already deleted (app might crash).

This is not very easy to test but I have definetely crashes and malfunctions for those two issues. E.g. NSMetadataQuery shows me results for documents which do not exist in iCloud because they have been deleted (but they existed on the deletion of the app).

Is there any easy solution to this? I thought about deleting the local iCloud data on the device when the app is launched for the first time - but how can this be done?

Solution

  • It can't be done. If you delete an iCloud document locally, you delete it everywhere-- eventually. The iCloud APIs have no concept of managing local copies independently of the iCloud service, so if you delete one-- even with the network down-- the iCloud ubiquity daemon will send a delete command to the service at the first opportunity.

    The closest approximation that current APIs would allow would be:

    • Check whether the network is reachable
    • If it's not reachable, do not attempt to access any iCloud documents (because as you note, the information might be stale).
    • If and when the network comes up, try to open all existing iCloud documents. (On iOS, iCloud updates are only downloaded on demand, so you need to create that demand).

    If that's not good enough (and let's face it, it's not good enough), file a bug with Apple and hope for the best.