两个控制器之间的通信

//A控制器中

- (void)toDo{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(nearbyToRootVcCommunication) name:@"nearbyToRootVcCommunication" object:nil];

}

//当B控制器中的viewDidLoad方法调用时，此方法也会被触发
-(void)nearbyToRootVcCommunication{
     NSLog(@"已回调");  
}

//=====================

//B控制器中

- (void)viewDidLoad{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(nearbyToRootVcCommunication) name:@"nearbyToRootVcCommunication" object:nil];
}