KVO vs NSNotification vs protocol/delegates?

Question

I have some idea of which to use when but the exact usage is still not clear to me. Can someone explain with example?

Answer 1

In my opinion KVO is better because of it's zero-overhead advantages. Notifications has overhead even if you aren't using/observing them. To improve that you can use different NotificationCenters but even with that some overhead will be there (correct me if I'm wrong). KVO is little complex but its worth when you have to observe lots of stuff.