 	*/
 	public private(set) var isUserInteractionEnabled: Bool {
 		get {
-			return mainViewContainer.userInteractionEnabled
+			return mainViewContainer!.userInteractionEnabled
 		}
 		set(value) {
-			mainViewContainer.userInteractionEnabled = value
+			mainViewContainer?.userInteractionEnabled = value
 		}
 	}
 	
 	/**
 		:name:	backdropViewContainer
 	*/
-	public private(set) var backdropViewContainer: UIView!
+	public private(set) var backdropViewContainer: UIView?
 	
 	/**
 		:name:	mainViewContainer
 	*/
-	public private(set) var mainViewContainer: UIView!
+	public private(set) var mainViewContainer: UIView?
 	
 	/**
 		:name:	leftViewContainer
 	*/
-	public private(set) var leftViewContainer: UIView!
+	public private(set) var leftViewContainer: UIView?
 	
 	/**
 		:name:	rightViewContainer
 	*/
-	public private(set) var rightViewContainer: UIView!
+	public private(set) var rightViewContainer: UIView?
 	
 	/**
 		:name:	leftContainer
 	*/
-	public private(set) var leftContainer: SideNavContainer!
+	public private(set) var leftContainer: SideNavContainer?
 	
 	/**
 		:name:	rightContainer
 	*/
-	public private(set) var rightContainer: SideNavContainer!
+	public private(set) var rightContainer: SideNavContainer?
 	
 	/**
 		:name:	mainViewController

	//
	private func prepareBackdropContainer() {
		backdropViewContainer = UIView(frame: view.bounds)
		backdropViewContainer.backgroundColor = options.backdropViewContainerBackgroundColor
		backdropViewContainer.autoresizingMask = .FlexibleHeight | .FlexibleWidth
		backdropViewContainer.layer.opacity = 0
		view.addSubview(backdropViewContainer)
	}
	
	//

	//
	//	:name:	prepareContainerToOpen
	//
	private func prepareContainerToOpen(inout viewController: UIViewController?, inout viewContainer: UIView?, state: SideNavState) {
		viewController?.beginAppearanceTransition(.Opened == state, animated: true)
		addShadow(&viewContainer)
		toggleWindow(shouldOpen: true)
	}
	
	//
	//	:name:	prepareContainerToClose
	//
	private func prepareContainerToClose(inout viewController: UIViewController?, state: SideNavState) {
		viewController?.beginAppearanceTransition(.Opened == state, animated: true)
		toggleWindow()
	}
	
	//
	//	:name:	prepareContainedViewController
	//
	private func prepareContainedViewController(inout viewContainer: UIView?, inout viewController: UIViewController?) {
		if let vc = viewController {
			if let c = viewContainer {
				addChildViewController(vc)
				vc.view.frame = c.bounds
				c.addSubview(vc.view)
				vc.didMoveToParentViewController(self)
			}
		}
	}
}
