iOS NotificationCenter intro
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The document discusses the observer pattern and iOS NotificationCenter. It explains that the observer pattern uses an event-driven approach to allow objects to register interest in events and be notified when those events occur. It provides code to demonstrate how to use iOS NotificationCenter by defining a notification name, adding an observer to receive notifications, posting a notification, and removing the observer. Potential pros and cons of using NotificationCenter are also mentioned.
iOS NotificationCenter intro
- 5. Observer Pattern • Event Driven • Easy to write • Decoupling
- 6. Observer Pattern Observer Subject Register / Unregister Notify
- 8. iOS NotificationCenter Observer Notification CenteraddObserver / removeObserver post notification Subject Call Selector
- 9. iOS NotificationCenter • Define new Notification.Name • Add Observer to NotificationCenter with callback Selector by given Notification.Name • Post event to NotificationCenter with associate Notification.Name • Remove Observer when stop listening
- 10. Code sample // Define key let key = Notification.Name("name") // Register to receive notification NotificationCenter.default.addObserver(self, selector: #selector(callback), name: key, object: nil) // Post notification NotificationCenter.default.post(name: key, object: nil) // Stop listening notification NotificationCenter.default.removeObserver(self, name: key, object: nil);
- 11. Pros & Cons • Easy to write • Less code • Decouple • …. • Hard to debug • Hard to maintain • Leak • ….
- 12. Q&A