NSNotification VS KVO

Question

I feel that i don\'t fully understand difference between KVO and NSNotification... They seem to be so similar... Could you make some example showing when is best to use one

Answer 1

KVO only works on values, NSNotification can be used for value changes but it can be used for anything and can carry a much greater payload.

For example, you could have an NSNotification posted whenever a file has finished downloading and the userInfo could contain the length of time it took, the number of bytes downloaded and the filesystem path that the file has been saved to.