UpdateChecker | Increase your app 's updates | iOS library

You said:

The UILabel can be displayed in different view controllers, so I can't tell it to register a NSNotification observer on load because that means every time the label is loaded it registers the observer again.

No, this is precisely what you should do for capturing updates to some Int value that needs to be reflected in multiple view controllers. Sure, every time a view controller is loaded (e.g. viewDidLoad) you’d add the NotificationCenter observer, and then remove the observer in deinit. But adding/removing observers is not an appreciably expensive process, so just do it. It sounds like the logical solution for the problem you describe.

FWIW, this does not seem like a good delegate-protocol candidate if multiple view controllers need to be informed of changes to this object. The delegate-protocol pattern is best used when there is a one-to-one relationship between an object and its delegate. But when you have many different view controllers that would like to be the “delegate”, in turn, then an observer pattern makes a lot more sense.

By the way, you reference something that “constantly receives updates” in conjunction with it being a “user default”. If there’s anything in your question that I’d take a hard look at, it would be the notion of using user defaults to capture something that isn’t really a default, but rather something that is presumably a model object that is frequently changing.

For example, let’s assume that I had defined some custom notification: