- (void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];

    CALayer *mask = [CALayer layer];
    mask.frame = self.maskView.bounds;
    mask.contents = (id)[[UIImage imageNamed:@"mask"] CGImage];
    _maskView.layer.mask = mask;
    _maskView.layer.masksToBounds = YES;
}