Updated app has saved the original data

What is the trick that some apps after 开发者_开发知识库update keep original data saved before update for example scores or settings. I would like to use it with pList, but have not found how yet.

tnx

There's no trick. Anything you save to user defaults or your app's documents directory will be preserved in an update.

Just save it to a file in your "Documents" folder, or use NSUserPreferences.

Both are retained across updates.

I would expect NSUserDefaults to handle it correctly, but I could be wrong.