iOS is backing up 28.0KB of some unknown data from

My app got rejected for not setting the "do not back up" attribute to two internal files I use (and store in /Documents). I've set the attribute, and it no longer backs up those files (~11.5MB).

It is still backing up 28kb of some data though. I removed all data from the /Documents folder and placed them to /tmp just to make sure that nothing in Documents could possibly be backed up. I verified /Documents is empty for my app after that change, and yet iCloud manages to find 28kb of data to back up.

How can I determine exactly what this data is to prevent the backup? I don't want to get rejected again so I'd like to verify that the app takes 0kb of backup storage on iCloud.

Thanks

This was the rejection notice:

2.23

We found that your app does not follow the iOS Data Storage Guidelines, which is required per the App Store Review Guidelines.

In particular, we found that on launch, your app stores 11.53 MB. To check how much data your app is storing:

Install and launch your app

Go to Settings > iCloud > Storage & Backup > Manage Storage

If necessary, tap "Show all apps"

Check your app's storage

The iOS Data Storage Guidelines indicate that only content that the user creates using your app, e.g., documents, new files, edits, etc., may be stored in the /Documents directory - and backed up by iCloud.

Temporary files used by your app should only be stored in the /tmp directory; please remember to delete the files stored in this location when the user exits the app.

Data that can be recreated but must persist for proper functioning of your app - or because customers expect it to be available for offline use - should be marked with the "do not back up" attribute. For NSURL objects, add the NSURLIsExcludedFromBackupKey attribute to prevent the corresponding file from being backed up. For CFURLRef objects, use the corresponding kCFURLIsExcludedFromBackupKey attribute.

For more information, please see Technical Q&A 1719: How do I prevent files from being backed up to iCloud and iTunes?.

It is necessary to revise your app to meet the requirements of the iOS Data Storage Guidelines. For discrete code-level questions, you may wish to consult with Apple Developer Technical Support. Please be sure to prepare any symbolicated crash logs, screenshots, or steps to reproduce the issues for when the DTS engineer follows up. For information on how to symbolicate and read a crash log, please see Tech Note TN2151 Understanding and Analyzing iPhone OS Application Crash Reports.

回答1:

It turns out the pre-compiled Google Analytics library keeps a small database called googleanalytics.sql in the /Library directory. Once I discovered this, I set the flag to "do not back up" for that file and it worked: I get 0kb backup.

回答2:

28k is probably just the directory structure and Apple bookkeeping. To be sure, hook up your device to the Xcode organizer and download the documents directory to your hard drive to take a peek.