@interface ViewController () <SWRevealViewControllerDelegate>

@property (strong, nonatomic) UIView* holderView;


#pragma mark - SWRevealViewController
        - (void)revealController:(SWRevealViewController *)revealController willMoveToPosition:(FrontViewPosition)position {
            if (position == FrontViewPositionRight) {
                self.holderView = [[UIView alloc] initWithFrame:CGRectMake(0.f, 0.f, self.view.bounds.size.width, self.view.bounds.size.height)];
                self.holderView.backgroundColor = [UIColor blackColor];
                self.holderView.alpha = 0;
                [self.view addSubview:self.holderView];

                [UIView animateWithDuration:0.3 animations:^{
                    self.holderView.alpha = 0.1;
                }];

            }
            else if (position == FrontViewPositionLeft){
                [UIView animateWithDuration:0.3 animations:^{
                    self.holderView.alpha = 0;
                    [self.holderView removeFromSuperview];
                }];
            }
        }