Problem with table loading cells after they come into view.

InfiniteTable.swift

import UIKit

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate  {
    var tableView: UITableView!
    private var fetchingMore = false
    var delay: Double!
    var items = [[Any]]()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        tableView = UITableView(frame: view.bounds, style: .plain)
        tableView.delegate = self
        tableView.dataSource = self
        tableView.register(CustomTableViewCell.self, forCellReuseIdentifier: "custom")
        let loadingNib = UINib(nibName: "LoadingCell", bundle: nil)
        tableView.register(loadingNib, forCellReuseIdentifier: "loadingCell")
        view.addSubview(tableView)
        tableView.translatesAutoresizingMaskIntoConstraints = false
        let layoutGuide = view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            tableView.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor),
            tableView.topAnchor.constraint(equalTo: layoutGuide.topAnchor),
            tableView.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor),
            tableView.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor)
        ])
        tableView.reloadData()
    }
    
    open func addNewComponent() {
        var blah = [[Any]]()
        for x in 0...12 {
            blah.append([1, self.randomString(length: 250)])
        }
        self.items.append(contentsOf: blah)
    }
    
    open func addNewCell(components: Array<Any>, path: IndexPath) -> UITableViewCell { return UITableViewCell() }
    
    func tempAddNewCell(components: Array<Any>, path: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "custom", for: path) as? CustomTableViewCell
        cell?.labMessage.text = "MessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessage"
        cell?.labTime.text = "\(path) h"
        cell?.labUerName.text = "Username"
        return cell!
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        if indexPath.section == 0 {
            let components = items[indexPath.row]
            return tempAddNewCell(components: components, path: indexPath)
        } else {
            let cell = tableView.dequeueReusableCell(withIdentifier: "loadingCell", for: indexPath) as! LoadingCell
            cell.spinner.startAnimating()
            return cell
        }
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if section == 0 {
            return items.count
        } else if section == 1 && fetchingMore {
            return 1
        }
        return 0
    }
    
    func numberOfSections(in tableView: UITableView) -> Int { return 2 }
    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        let offsetY = scrollView.contentOffset.y
        let contentHeight = scrollView.contentSize.height
        if offsetY > contentHeight - scrollView.frame.height * 2 {
            if !fetchingMore { beginBatchFetch() }
        }
    }
    
    func beginBatchFetch() {
        fetchingMore = true
        tableView.reloadSections(IndexSet(integer: 1), with: .none)
        DispatchQueue.main.asyncAfter(deadline: .now() + (self.delay ?? 0.1), execute: {
            self.addNewComponent()
            self.fetchingMore = false
            self.tableView.reloadData()
        })
    }
        
}

InfiniteTableCustomCell.swift

class CustomTableViewCell: UITableViewCell {
    let imgUser = UIImageView()
    let labUerName = UILabel()
    let labMessage = UILabel()
    let labTime = UILabel()

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        imgUser.backgroundColor = UIColor.blue

        imgUser.translatesAutoresizingMaskIntoConstraints = false
        labUerName.translatesAutoresizingMaskIntoConstraints = false
        labMessage.translatesAutoresizingMaskIntoConstraints = false
        labTime.translatesAutoresizingMaskIntoConstraints = false

        contentView.addSubview(imgUser)
        contentView.addSubview(labUerName)
        contentView.addSubview(labMessage)
        contentView.addSubview(labTime)

        let viewsDict = [
            "image" : imgUser,
            "username" : labUerName,
            "message" : labMessage,
            "labTime" : labTime,
            ] as [String : Any]

        contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-[image(10)]", options: [], metrics: nil, views: viewsDict))
        contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[labTime]-|", options: [], metrics: nil, views: viewsDict))
        contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-[username]-[message]-|", options: [], metrics: nil, views: viewsDict))
        contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-[username]-[image(10)]-|", options: [], metrics: nil, views: viewsDict))
        contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-[message]-[labTime]-|", options: [], metrics: nil, views: viewsDict))
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

}

Used this tutorial: https://github.com/RobCanton/Swift-Infinite-Scrolling-Example/tree/master/InfiniteScrollingExample-End

I made a bunch of tweaks such as inserting certain cells; ended up deleting them for this gist to keep concise... a little. When I use the tutorial's ViewController, the infinite table works seamlessly. When you run the above code, you'll see that the table's view jumps up then back down. I think I've deduced it down to the point of the "beginBatchFetch()" func being the problem.

When viewing the problem, it caught my attention that the appending items and then the insertion of cells in correspondence to those items happened at different times. The appending of items happens at the exact time but the insertion of cells happens when the table is barely in view of the bottom.

Can someone help out?