iOS: NSNotificationCenter的方法addObserverForName:object:queue:usingBlock:

- (id)addObserverForName:(NSString *)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *))block

NSNotificationCenter *center = [NSNotificationCenter defaultCenter];

NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];

self.localeChangeObserver = [center addObserverForName:NSCurrentLocaleDidChangeNotification object:nil

    queue:mainQueue usingBlock:^(NSNotification *note) {

 

        NSLog(@"The user's locale changed to: %@", [[NSLocale currentLocale] localeIdentifier]);

    }];

NSNotificationCenter *center = [NSNotificationCenter defaultCenter];

[center removeObserver:self.localeChangeObserver];