How the application upgrade works in iPhone

Question

Hello all,

I am planning to post an application for iPhone in iTunes Store. Soon I am gonna provide an upgrade for it. But later to current version. I want to know how the upgrade system works in iPhone. Like does it replaces the whole application and reinstall it deleteing the previous database or it adds the new version keeping the database and all the same.

Answer 1

Upgrades replace the app bundle, but anything else in your sandbox (like the Documents folder, caches, preferences, etc) are preserved in place.