What's the meaning of this piece of code?

Question

[[NSNotificationCenter defaultCenter] addObserver:self 
                                         selector:@selector(requestAddressUpdatedNotification:) 
                                             name:MTAddressUpdatedNotification 
                                           object:nil];

Can anyone tell me what will happen if I write this piece of code in my program ?

And when will the method requestAddressUpdatedNotification be called?

You might like to have a look at [the Observer Pattern](http://en.wikipedia.org/wiki/Observer_pattern) — James Webster, Aug 14 '12 at 08:54

score 4 · Answer 1 · edited Aug 14 '12 at 08:55

4

The code informs the default NSNotificationCenter to notify your object (self) when a MTAddressUpdatedNotification NSNotification occurs and to trigger requestAddressUpdatedNotification: method which must be defined (within @implementation…@end) in the same class.

edited Aug 14 '12 at 08:55

F. Orvalho

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answered Aug 14 '12 at 08:44

Global nomad

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So you mean if MTAddressUpdatedNotification occurs and requestAddressUpdatedNotification will be called? – generalzyq Aug 14 '12 at 08:46
Yes, when a MTAddressUpdatedNotification is posted, your requestAddressUpdatedNotification: will be triggered or in Objective-C parlance "receive a message". – Global nomad Aug 14 '12 at 08:50

What's the meaning of this piece of code?

1 Answers1