Correct management of addObserverForName:object:queue:usingBlock:

Question

I\'m still new to blocks in objective-c and wondering if I have this psuedo code correct. I\'m not sure if it\'s enough to just remove the observer or if i have to call removeOb

Answer 1

You should not unregister in the register block. Instead, store the token returned from addObserverForName (in this case, your scanComplete) as an instance variable or in a collection that is an instance variable, and unregister later when you're about to go out of existence (e.g. in dealloc). What I do is keep an NSMutableSet called observers. So:

id ob = [[NSNotificationCenter defaultCenter] 
     addObserverForName:@"whatever" object:nil queue:nil 
     usingBlock:^(NSNotification *note) {
        // ... whatever ...
}];
[self->observers addObject:ob];

And then later:

for (id ob in self->observers)
    [[NSNotificationCenter defaultCenter] removeObserver:ob];
self->observers = nil;