UILabel电子表显示

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    //label
    label=[[UILabel alloc]initWithFrame:CGRectMake(50, 100, 200, 200)];
    label.backgroundColor=[UIColor redColor];
    [self.view addSubview:label];
    
    //定时器
    [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateTime) userInfo:nil repeats:YES];
    
    dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"HH:mm:ss"];
    
}
- (void)updateTime
{
    label.text = [dateFormatter stringFromDate:[NSDate date]];
}