自动消失的小提示-结合xib

@property (weak, nonatomic) IBOutlet UILabel *littleAlert;

- (IBAction)signUp:(UIButton *)sender {

    

    [self showLittleAlert];

}

-(void)showLittleAlert{

    self.littleAlert.alpha = 1.f;

    self.littleAlert.hidden = NO;

    [UIView animateWithDuration:2.f animations:^{

        self.littleAlert.alpha = 0.f;

    }completion:^(BOOL finished) {

        self.littleAlert.hidden = YES;

    }];

}