 /// type identifiers for dragging operation
 private enum PboardType {
     static let rows = "rows"
-    static let objects = "objects"
 }
 
 

        // obtain original rows from paste board
        guard
            let data = info.draggingPasteboard().data(forType: PboardType.rows),
            let sourceRows = NSKeyedUnarchiver.unarchiveObject(with: data) as? IndexSet,
            let draggingItems = info.draggingPasteboard().propertyList(forType: PboardType.objects) as? [Any] else { return false }
        
        let destinationRow = row - sourceRows.count(in: 0...row)  // real insertion point after removing items to move
        let destinationRows = IndexSet(destinationRow..<(destinationRow + draggingItems.count))

        // store row index info to pasteboard
        let rows = NSKeyedArchiver.archivedData(withRootObject: rowIndexes)
        pboard.setData(rows, forType: PboardType.rows)
        
        return true
    }
