The Application is a singleton which maintains a reference to the app delegate. You can always access your app delegate using:
[UIApplication sharedApplication].delegate
You may need to cast the return to your own app delegate class to get rid of warnings. Even better, write an accessor that returns your upcast app delegate:
#pragma mark access to app delegate etc.
+ (MyAppDelegateClass*) sharedAppDelegate; {
return (MyAppDelegateClass*)[[UIApplication sharedApplication] delegate];
}