If viewWillDisappear isn't working for you, try adding an observer in NSNotification center, which calls a method when the application didEnterBackground. Like so:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(enteredBackground:)
name:UIApplicationDidEnterBackgroundNotification
object:nil];
Then add your code into this method:
-(void)enteredBackground:(NSNotification *)notification {
}
Hope this helps!
UPDATE
Okay, so from where you want to acces the audio object in the about us view, try this:
HomeViewController *HomeVC = [HomeViewController alloc] init];
HomeVC.audioPlayer...//then do what you want with it
As long as you have declared the audio object in the home VC then this should work.
Make sure you have imported the homeview controller in one of the about us view controller, files as well.