 
 public protocol ScrollBarController : ScrollBarDelegate {
     var scrollBar: ScrollBar! { get }
-    var selectedViewController: UIViewController! { get set }
     var _selectedViewController: UIViewController! { get set }
     weak var delegate: ScrollBarControllerDelegate? { get set }
     var isTransitioningFromViewController: Bool { get set }

            return _selectedViewController
        }
        set {
            _selectedViewController = newValue
        }
    }


                    duration: NSTimeInterval(0), options: UIViewAnimationOptions(rawValue: 0),
                    animations: { [unowned self] (finished) -> Void in
                        //toViewController の viewWillAppear の実行が終わったあとに実行する
                        self.selectedViewController = didSelectController!
                        
                        if self.delegate != nil {
