+ (void)showOnViewController:(UIViewController*)parentVC completion:(MYVCCompletionBlock)completion
{
    MYVC *notificationsViewController
    = [parentVC.storyboard instantiateViewControllerWithIdentifier:NSStringFromClass(self)];
   notificationViewController.completion = completion

   [notificationsViewController willMoveToParentViewController:parentVC];
   [notificationsViewController viewWillAppear:YES];

    // настраиваешь иерархию вью
    // в случае, если откуда угодно - я бы добавлял к window

    [UIView animateWithDuration:
	             animations:
		     completion:^(BOOL finished)
    {
        [notificationsViewController viewDidAppear:YES];
        [parentVC addChildViewController:self];
        [notificationsViewController didMoveToParentViewController:parentVC];
    }];
}