     optional func swipeViewItemDistance(swipeView: HFSwipeView) -> CGFloat
 }
 
+
+// MARK: - HFSwipeViewDelegate
 @objc public protocol HFSwipeViewDelegate: NSObjectProtocol {
     optional func swipeView(swipeView: HFSwipeView, didFinishScrollAtIndexPath indexPath: NSIndexPath)
     optional func swipeView(swipeView: HFSwipeView, didSelectItemAtPath indexPath: NSIndexPath)
     optional func swipeView(swipeView: HFSwipeView, didChangeIndexPath indexPath: NSIndexPath)
 }
 
+
+// MARK: - HFSwipeViewFlowLayout
 class HFSwipeViewFlowLayout: UICollectionViewFlowLayout {
     
     weak var swipeView: HFSwipeView!

        //        log("\(#function): real -> \(indexPath.row)")
    }
}

// MARK: - UICollectionViewDataSource
extension HFSwipeView: UICollectionViewDataSource {

        collectionView!.contentSize = contentSize
        log("successfully set content size: \(self.collectionView!.contentSize)")
    }
}



// MARK: - Public APIs
extension HFSwipeView {
    public func layoutViews() {
        
        log("\(#function)")
