title: ios 7 custom present and dismiss transition
body: <p>I'm making custom present and dismiss transitions and have some problems with it. What I want to do is repeat this cool deep animations in iOS 7 (when we open/close some app).
  I have First and Second Controllers. All animations are in First controller (it supports UIViewControllerTransitioningDelegate and UIViewControllerAnimatedTransitioning). So, I'm just checking: if it is presenting - I'm doing one animations (scaling up first and second view), if it is dismissing - I'm doing another animation (scaling down first and second view). Present animation works fine, the problem occurs with dismiss animation. In some reason when I'm scaling down my second controller (it is UINavigationController), I see black background behind it (and it's wrong, because I want to see my First controller while it's scaling down). Here is my code from First Controller  </p>
  
  <pre><code>- (void)animateTransition:(id&lt;UIViewControllerContextTransitioning&gt;)transitionContext {
      UIView *transitionView = [transitionContext containerView];
  
      id toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
      id fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
  
      BOOL isPresenting;
  
      isPresenting = [toViewController isKindOfClass:[UINavigationController class]];
  
      UINavigationController *navigator = isPresenting ? toViewController : fromViewController;
  
      if (isPresenting) {
          [transitionView addSubview:navigator.view];
          navigator.view.transform = CGAffineTransformMakeScale(0.1, 0.1);
          navigator.view.alpha = 0;
      }
  
      navigator.view.center = self.startButton.center;
  
      void(^AnimationBlock)(void) = ^ {
          if (isPresenting) {
              navigator.view.transform = CGAffineTransformMakeScale(1, 1);
              self.view.transform = CGAffineTransformMakeScale(4, 4);
              navigator.view.alpha = 1;
              self.startButton.alpha = 0;
          } else {
              navigator.view.transform = CGAffineTransformMakeScale(0.1, 0.1);
              self.view.transform = CGAffineTransformMakeScale(1, 1);
              navigator.view.alpha = 0;
              self.startButton.alpha = 1;
          }
      };
  
      [UIView animateWithDuration:1
                            delay:0.0f
           usingSpringWithDamping:50.0
            initialSpringVelocity:4
                          options:UIViewAnimationOptionLayoutSubviews
                       animations:^{
                           AnimationBlock();
      } completion:^(BOOL finished) {
          [transitionContext completeTransition:YES];
          if (!isPresenting) {
              [navigator.view removeFromSuperview];
          }
      }];
  }
  
  - (void)completeTransitionInContext:(id&lt;UIViewControllerContextTransitioning&gt;)transitionContext{
      [transitionContext completeTransition:YES];
  }
  
  
  - (NSTimeInterval)transitionDuration:(id&lt;UIViewControllerContextTransitioning&gt;)transitionContext{
      return 1;
  }
  
  
  - (id &lt;UIViewControllerAnimatedTransitioning&gt;)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source {
      return self;
  }
  
  - (id &lt;UIViewControllerAnimatedTransitioning&gt;)animationControllerForDismissedController:(UIViewController *)dismissed {
      return self;
  }
  </code></pre>
  
  <p>Please tell me if I should to provide some additional code or screens.
  Thanks in advance!</p>