通知传值

传值B页面:

[NSNotificationCenter defaultCenter] postNotificationName:@"cityName" object:self userInfo:dict];

接收A页面:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(cityNameNotification:) name:@"cityName" object:nil];

- (void)cityNameNotification:(NSNotification *)notification {

    NSDictionary *nameDictionAry = [notification userInfo];

    [backButton setTitle:[nameDictionAry objectForKey:@"State"] forState:UIControlStateNormal];

}