Several methods could be used here.
You could use a property on custom singleton class to hold onto and share the object.
This is a good pattern here - Create singleton using GCD's dispatch_once in Objective C
You could use the AppDelegate class and keep it as a property on the class but that pattern wise isn't so good IMHO as it treats the AppDelegate as a junk-yard for things you don't know what to do with and you also end up with ugly casts all over the place.
((MyAppDelegate *)[[UIApplication sharedApplication] delegate]).acaccountobject
Technically the singleton and the AppDelegate are the same principal but as mentioned the AppDelegate is not a junkyard.