i have developed an app that can download mp3 files (nearly 6 to 8 mb of size) from online and stored in NSDocumentDirectory. my app get rejected today and says that
As per the iOS Storage Guidelines (which can be found at http://developer.apple.com/icloud/documentation/data-storage/) you should put all user-generated content in the Documents directory and all re-downloadable content in the Caches directory. So you should be fine putting the sqLite database there.
The background on this is that starting with iOS 5 the Documents directory is backed up to iCloud. As a lot of apps tend to store their complete data there the iCloud backups get rather large, which uses up the free space and creates network traffic, both of which in turn anger the user because he/she wonders why. To mitigate this Apple now seems to take a much closer look on what is saved into the Documents directory and if this is possibly regeneratable content (e.g. downloadable files).
Beware, that the Caches directory can and will be purged on iOS 5 by the operating system at times when the free space on the device gets low. Thus your app cannot longer just assume that everything is there as it was before but you rather have to re-check every time you access something out of your cache.
Hope this helps...!