Building an authentication layer in iOS

coming from over a decade of web application where cookie/session are the only form of auth-technology, I wonder what I could use to build, if it does not already exists, a re-usable authentication layer for an iOS application. Something that I could plug and switch on/off for my next built applications.

I am not talking about a stri开发者_如何转开发ct security mechanism, but at least a module which could allow to have different users, where they can play with the application and apply local changes to it. At application start up, user would be prompted to enter user and password, then trough all the application lifecycle the user is 'remembered', and then forgotten at app shutdown.

The module could perform several authentication. The simplest mechanism I would like to start with is user and password stored into app, but I would like to extend in the future by adding authentication trough a central server, or a web service, or whatever is possible with it.

thanks

Mac OS X and iOS Secure Coding Guide