In ARC do we need to send removeObserver: explicitly?

Question

Do we have to send removeObserver: explicitly for objects that have been added as observers to an NSNotificationCenter before?

I am bit con

Answer 1

Removing the observer is always a smart idea. If you don't remove the observer, messages will still be sent, even if the object was deallocated. It might even be attached to another object, which would definitely lead to serious trouble.