         
         if iOS8 {
             if let cntentViewStoryboardID = contentViewStoryboardID {
-                contentViewController = storyboard?.instantiateViewControllerWithIdentifier(cntentViewStoryboardID) as? UIViewController
+                contentViewController = storyboard?.instantiateViewControllerWithIdentifier(cntentViewStoryboardID)
             }
             if let lftViewStoryboardID = leftMenuViewStoryboardID {
-                leftMenuViewController = storyboard?.instantiateViewControllerWithIdentifier(lftViewStoryboardID) as? UIViewController
+                leftMenuViewController = storyboard?.instantiateViewControllerWithIdentifier(lftViewStoryboardID)
             }
             if let rghtViewStoryboardID = rightMenuViewStoryboardID {
-                rightMenuViewController = storyboard?.instantiateViewControllerWithIdentifier(rghtViewStoryboardID) as? UIViewController
+                rightMenuViewController = storyboard?.instantiateViewControllerWithIdentifier(rghtViewStoryboardID)
             }
         }
         

    
    private func removeMotionEffects(targetView: UIView) {
        
        if let targetViewMotionEffects = targetView.motionEffects {
            for effect in targetViewMotionEffects {
                targetView.removeMotionEffect(effect as! UIMotionEffect)
            }
        }

        
        if interactivePopGestureRecognizerEnabled,
            let viewController = contentViewController as? UINavigationController
            where viewController.viewControllers.count > 1 && (viewController.interactivePopGestureRecognizer?.enabled ?? false) {
                return false
        }
        
