Unfortunately i received this from Apple today. Before submitting your app, make sure check this out first.

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

In particular, we found that the app content is not being stored appropriately.

The iOS Data Storage Guidelines specify:

“1. Only documents and other data that is user-generated, or that cannot otherwise be recreated by your application, should be stored in the /Documents directory and will be automatically backed up by iCloud.

2. Data that can be downloaded again or regenerated should be stored in the /Library/Caches directory. Examples of files you should put in the Caches directory include database cache files and downloadable content, such as that used by magazine, newspaper, and map applications.

3. Data that is used only temporarily should be stored in the /tmp directory. Although these files are not backed up to iCloud, remember to delete those files when you are done with them so that they do not continue to consume space on the user’s device.

4. Use the “do not back up” attribute for specifying files that should remain on device, even in low storage situations. Use this attribute with data that can be recreated but needs to persist even in low storage situations for proper functioning of your app or because customers expect it to be available during offline use. This attribute works on marked files regardless of what directory they are in, including the Documents directory. These files will not be purged and will not be included in the user’s iCloud or iTunes backup. Because these files do use on-device storage space, your app is responsible for monitoring and purging these files periodically.”

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

It would be appropriate 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.