     private func configureToolbarStackConstraints() {
         guard let toolbarStackConstraints = toolbarStackConstraints else { return }
         NSLayoutConstraint.activateConstraints(toolbarStackConstraints)
-    }
-    
-    private var scrollViewConstraints: [NSLayoutConstraint]? {
-        guard let
-            leading = scrollView.leadingAnchor.constraintEqualToAnchor(leadingAnchor),
-            trailing = scrollView.trailingAnchor.constraintEqualToAnchor(trailingAnchor),
-            top = scrollView.topAnchor.constraintEqualToAnchor(topAnchor),
-            bottom = scrollView.bottomAnchor.constraintEqualToAnchor(bottomAnchor)
-            else { return nil }
-        return [leading, trailing, top, bottom]
     }
     
     private var toolbarConstraints: [NSLayoutConstraint]? {

        toolbarStack.addArrangedSubview(clearButton)
        toolbar.addSubview(toolbarStack)
        addSubview(toolbar)
        
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        toolbar.translatesAutoresizingMaskIntoConstraints = false
        toolbarStack.translatesAutoresizingMaskIntoConstraints = false
        
        configureScrollViewConstraints()
        configureToolbarConstraints()
        configureToolbarStackConstraints()
    }
    
    private func configureScrollViewConstraints() {
        guard let scrollViewConstraints = scrollViewConstraints else { return }
        NSLayoutConstraint.activateConstraints(scrollViewConstraints)
    }
    
    private func configureToolbarConstraints() {

        }
    }
    
    func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if !decelerate {
            currentOffsetX = scrollView.contentOffset.x
        }
    }
    
    func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
        currentOffsetX = scrollView.contentOffset.x
    }
    
}
