iphone: preserve user data against app update

I'm developing my first iphone app that allow users to take pictures and store them & other meta data in the App's Documents folder.

If in 开发者_开发百科the future I provide version updates to users, does it affect the user-created data? If it does, then what is the best strategy to preserve the data?

Thanks a lot

No, any data saved in the user Documents folder will remain intact during and after an update.

EDIT:

Here is the official link: iOS Application Programming Guide.

Files Saved During Application Updates

When a user downloads an application update, iTunes installs the update in a new application directory. It then moves the user’s data files from the old installation over to the new application 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.