class ViewController: UITableViewController {

    var items = [Int]()

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.backgroundColor = .white
        tableView.tableFooterView = UIView()
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "CELL_ID")

        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
            self.addMoreRows([1,2,3,4,5])
        }

        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            self.addMoreRows([6,7,8,9,10])
        }

    }

    private func addMoreRows(_ data: [Int]) {

        self.items.append(contentsOf: data)

        var indexPaths = [IndexPath]()

        for i in 0...items.count - 1 {
            indexPaths.append(IndexPath(row: i, section: 0))
        }

        tableView.insertRows(at: indexPaths, with: .left)
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "CELL_ID", for: indexPath)
        cell.textLabel?.text = "Cell #(indexPath.row)"
        return cell
    }
}