Does updating iOS apps delete library directory files?

I keep save files in a private directory in my iPad app, namely the one returned when I use:

paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
documentsDirectory = [paths objectAtIndex:0];
documentsDirectory = [documentsDirectory stringByAppendingPathComponent:@"Private Documents"]; 

Notice that I also append a subdirectory to it. When I update the app, users are telling me that their progress in the app is getting destroyed. Are files in this NSLibraryDirectory destroyed every time I update the app? If so, should I be using NSDocumentDirectory instead?

Additionally, is there no way to make a further update to my app to remedy this without destroying all my my current users' 开发者_开发知识库save files? It doesn't seem like there is.

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.

This is provided by apple officially. See this link : iOS Developer Library - File Saved During App Updates

I would also like to add this info as a personal experience with a big online game. You can't rely at 100% that your "Document" and "Library" folder will always be there. In fact, you can't rely that your app folder will still be at the same place on your device after an update.

Let me explain it a little bit more. When you install an app on your device, the real path will be /var/mobile/Applications/[some class id]/[your app].app/... We're not sure who defines the class id of your app (either the iOS or app store), but this Id can change when updating the game resulting in having your app in a totaly different folder so your old files aren't there anymore. Our QA experienced it and our users too.

I won't go through the details on how we found that out and how we managed to get around this (private company stuff, usual shit...), but you need to consider it if you're doing an app that affects tons of users and might be updated a couple of times. It might have been fixed since, but it's always good to have a backup plan.

You should save them in the Documents folder, it is persistent across updates.

Monotouch: documentsDirectory = environment.specialfolder.personal;

Objective-C: NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)