在两个viewcontroller之间的delegation有问题

第一个viewcontroller是排行榜菜单，里面有一个按钮指示到第二个viewcontroller中,第二个是小游戏，如果玩家输了，最高分变动，就更新排行榜。在玩家完成游戏时建了带两个按钮的UIAlertView，一个是主菜单，另一个是重新开始，我的代码如下：我想通过delegation更新排行榜

@protocol highScoreProtocol <NSObject>

       -(void)updateHighScore:(int) score;


       @end

       @interface ViewController : UIViewController <UIAlertViewDelegate> 
       @property (nonatomic) int score;
       @property (nonatomic, weak) id <highScoreProtocol> delegateHighScore;
       @implementation ViewController
       @synthesize score=_score;
       @synthesize delegateHighScore=_delegateHighScore;

           -(void)lostGame{
           [self.delegateHighScore updateHighScore:self.score]; 

       UIAlertView *losingScreen=[[UIAlertView alloc]initWithTitle:@"Game Over" message:[NSString stringWithFormat:@"Your Score Is %d", self.score] delegate:self cancelButtonTitle:@"Main Menu" otherButtonTitles:@"Restart", nil]; 
           }

       -(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
             if (buttonIndex==0) {


           } else if (buttonIndex==1){

           }
       }

   @end

           @interface MenuVC : UIViewController <highScoreProtocol>
           @property (weak, nonatomic) IBOutlet UILabel *labelHighScore;
   @end


@implementation MenuVC

- (void)viewDidLoad
{
   [super viewDidLoad];
   ViewController *vc=[[ViewController alloc]init];
   vc.delegateHighScore=self;

}

-(void)updateHighScore:(int)score{
   if (score>[self.labelHighScore.text integerValue]) { 
       self.labelHighScore.text=[NSString stringWithFormat:@"%d", score];
   }
   NSLog(@"does this method even run");
}