Question

I’ve got an iPhone app that loads user information as an XML file and stores it as as NSUserDefaults. The defaults are persisting between launches, however, and I’d like to force a reload each launch. Presently the initial download is in the applicationDidFinishLaunching method of my app delegate. Is there a way I can detect whether an app has been ‘woken’ (i.e. opened again but perhaps not launched because of iOS 4 persistence) or can I delete these defaults when an app ‘sleeps’?

Answer 1

In short, I would try doing that setup / tear down work in applicationDidEnterForeground: or didBecomeActive: and their respective mirrors.

If you need a little more guidance, check out the official docs here:
I would recommend following the standard procedures laid out in the following docs:
http://developer.apple.com/LIBRARY/IOS/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/StandardBehaviors/StandardBehaviors.html#//apple_ref/doc/uid/TP40007072-CH4-SW7

With a snippet being:

When your application’s applicationDidEnterBackground: or
applicationWillTerminate: method is called, build your property list
and save it as an application preference. Then, in your
application:didFinishLaunchingWithOptions: method, load the property
list from preferences and use it to create and configure any
additional view controllers you need.