     }
     
     private func adjustContentInset(height: CGFloat, duration: NSTimeInterval, options: UIViewAnimationOptions, animated: Bool) {
-        bottomInsetConstraint.constant = height
+        bottomInsetConstraint?.constant = height
         view.setNeedsLayout()
         
         if (animated) {

            transition.type = kCATransitionMoveIn
            transition.subtype = kCATransitionFromRight
            transition.duration = VisualFactory.Metrics.defaultAnimationDuration
            self.containerView.layer.addAnimation(transition, forKey: nil)
        }
        
        // retain new view controller

        super.updateView()
        
        navigationItem.rightBarButtonItem?.customView?.hidden = !currentStepViewController!.finalizesFlow
        stepNumberLabel?.text = "\(currentStepViewController!.stepNumber)."
        stepIndicationLabel?.text = currentStepViewController!.stepIndication
    }
    
    override func configureView() {
