Keep uitableview static when inserting rows at the top

[Swift]KeepUItableviewStatic

private func addListBubbleCellsWithCount(count: Int) {
        var contentOffset = self.tableView.contentOffset
        
        UIView.setAnimationsEnabled(false)
        
        var indexPaths = [NSIndexPath]()
        var heightForNewRows: CGFloat = 0
        
        for var i = 0; i < count; i++ {
            let indexPath = NSIndexPath(forRow: i, inSection: 0)
            indexPaths.append(indexPath)
            
            heightForNewRows += heightForCellAtIndexPath(indexPath)
        }
        
        contentOffset.y += heightForNewRows
        
        tableView.beginUpdates()
        tableView.insertRowsAtIndexPaths(indexPaths, withRowAnimation: UITableViewRowAnimation.None)
        tableView.endUpdates()
        
        UIView.setAnimationsEnabled(true)
        self.tableView.setContentOffset(contentOffset, animated: false)
    }
    
    private func heightForCellAtIndexPath(indexPath: NSIndexPath) -> CGFloat {
        let messageData = messagesDataArray[indexPath.row]
        return LINBubbleCell.getHeighWithMessageData(messageData)
    }