         super.viewDidLayoutSubviews()
         
         if case nil = focusView.superview, collectionView.numberOfItems(inSection: 0) > 0, let cell = collectionView.cellForItem(at: IndexPath(item: 0, section: 0)) {
+            focusView.translatesAutoresizingMaskIntoConstraints = true
+            focusView.autoresizingMask = [.flexibleWidth, .flexibleHeight, .flexibleTopMargin, .flexibleLeftMargin]
             focusView.frame = cell.frame
             collectionView.addSubview(focusView)
         }

    func menuViewController(viewController: PagingMenuViewController,  focusViewDidEndTransition focusView: PagingMenuFocusView)
}

public protocol PagingMenuViewControllerDelegate: class {
    func menuViewController(viewController: PagingMenuViewController, didSelect page: Int)
}

        collectionView.setContentOffset(offset, animated: animated)
    }
    
    public func registerFocusView(view: PagingMenuFocusView) {
        focusView = view
    }
    
    public func registerFocusView(nib: UINib) {
        focusView = nib.instantiate(withOwner: self, options: nil).first as! PagingMenuFocusView
    }
    
    public func register(nib: UINib?, forCellWithReuseIdentifier identifier: String) {
        collectionView.register(nib, forCellWithReuseIdentifier: identifier)
    }
