gistfile1.m

        __weak typeof(self) weakSelf = self;
        [[NSNotificationCenter defaultCenter] addObserverForName:ACAccountStoreDidChangeNotification
                                                          object:nil
                                                           queue:nil
                                                      usingBlock:^(NSNotification *note) {
                                                          __strong typeof(weakSelf) strongSelf = weakSelf;
                                                          [strongSelf requestProfileInformation];
                                                      }];