 {
     static let kBarHeight:CGFloat = 64
     
-    private weak var viewBar:VParentBar!
-    private weak var layoutBarTop:NSLayoutConstraint!
+    private weak var controller:CParent!
+    private weak var viewBar:VParentBar?
+    private weak var layoutBarTop:NSLayoutConstraint?
     private let kAnimationDuration:TimeInterval = 0.3
     
     convenience init(controller:CParent)

        self.init()
        clipsToBounds = true
        backgroundColor = UIColor.white
        
        let viewBar:VParentBar = VParentBar(
            controller:controller)
        self.viewBar = viewBar

            constant:0)
        
        addConstraints([
            layoutBarTop!,
            layoutBarHeight,
            layoutBarLeft,
            layoutBarRight])
    }
    
    //MARK: public
    
    func mainView(view:VView)
    {
        if viewBar == nil
        {
            addSubview(view)
        }
        else
        {
            insertSubview(view, belowSubview:viewBar!)
        }
        
        view.constraints(
            initialLeft:0,
            initialRight:0,
