Quick question, in the code snippit:

@interface AudioTestViewController : UIViewController {
IBOutlet UILabel *pluggedLabel;

AudioNotifications *myNot;

}

@property (nonatomic, retain) IBOutlet UILabel *pluggedLabel;

@end

…do I really need the “IBOutlet” inside the interface declaration? Won’t it be ok, *only* to have it in the property declaration later?

@protocol AudioNotificationsDelegate <NSObject>

Your comment system ate the angle brackets.

“It seems to be standard to not retain the delegate but only assign it. Don’t ask me why.”

Because in most cases, the delegate owns (and therefore retains) the delegating object. If both objects retained each other, the delegate would not be deallocated when it is released by its own parent (because its retain count is still > 0). In the end, both delegate and delegating object will never be deallocated.

“But in order to be able to use the respondsToSelector method I found I needed to cast it to an NSObject.”

You can avoid the NSObject type cast by requiring your protocol to conform to the NSObject protocol:

@protocol AudioNotificationsDelegate
…
@end

NSObject is not only a class but there is also an NSObject protocol that declares the same methods as the class. Thus, every NSObject subclass conforms to the NSObject protocol. In practice, including in your protocol definition means that your delegate must be an instance of an NSObject subclass.