App Updates, NSURL, and Documents Directory

Question

I have an app in the app store that uses Core Data to persist much of the data. The exception is storing images. I store images in subdirectories to the Documents directory

Answer 1

I think what you're looking for is the following:

NSString *appDocumentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

Answer 2

You should use relative URLs to store references to files. The absolute URL is likely to change after an app update

Files Saved During App Updates

When a user downloads an app update, iTunes installs the update in a new app directory. It then moves the user’s data files from the old installation over to the new app directory before deleting the old installation. Files in the following directories are guaranteed to be preserved during the update process:

• Application_Home/Documents
• Application_Home/Library

Although files in other user directories may also be moved over, you should not rely on them being present after an update.

https://developer.apple.com/library/ios/#DOCUMENTATION/iPhone/Conceptual/iPhoneOSProgrammingGuide/PerformanceTuning/PerformanceTuning.html

Thx to the sandbox, the application home is also the user home. So it is possible to use the unix tilde which is a short hand to the user home, i.e. ~/Documents, ~/Library and so on.

Use -[NSString stringByAbbreviatingWithTildeInPath] to turn a full path into a relative ~ path. And reverse it with -[NSString stringByExpandingTildeInPath].