is removeObserver necessary on dealloc?

问题

In one of my view controller, it adds itself as observer of UITextViewTextDidEndEditingNotification notification, like the following does

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(done:) name:UITextViewTextDidEndEditingNotification object:nil];

Now I am wondering - do I need to do the following when the view controller is dealloc'd

[[NSNotificationCenter defaultCenter] removeObserver:self];

回答1:

yes, you should always remove any observers when they're being dealloc'd. otherwise the notification center will keep references to the now-dealloc'd objects around and continue to try to forward notifications to them.

来源：https://stackoverflow.com/questions/8665575/is-removeobserver-necessary-on-dealloc