Updating iPhone app removed the older version data

Question

I am developing a social application for iOS using Objective-c. But when I published the newer version of my app and upgraded it using App Store, all of my older application data has been removed while every thing in both versions is the same like Bundle Identifier, Provisioning Profile, Signing Certificate. But I am confused why some thing like that happened. I was wondering if anyone could help me. This is too important for me, because this problem forces users to register again in the application.

update: I save data in the documents and also using core data

Answer 1

It might not be cleared just the path of the files changed, for example lets say you save the path of a photo like this :

/data/Containers/Data/Application/B42FE84A-E031-4A2C-AEA7-8D77AEAA389C/Documents/Photo.jpg

when you update the app the path will look like this because iOS will change app documents folder

/data/Containers/Data/Application/757455E1-355B-4040-8ABB-85F39D650A1E/Documents/Photo.jpg

so the file still exist but the path have changed and since you are saving the path the app won't find it because it was changed

i recommend saving only file name not the whole path