NSNotificationCenter for iOS and Mac

Guides | Tutorial By 2 years ago

If you’ve ever needed to have an object with multiple delegates you may have created an array and then added each of your delegates to it. This does work but there’s a simpler way which is much easier to implement. Using the NSNotificationCenter you can have objects subscribe to the events/messages they want to know about and get called whenever that ‘event’ takes place. The Cocoa framework uses this as well, and let’s you subscribe to things such as an app entering the background, changing orientations, when it’s running out of memory and when the keyboard is presented or dismissed.