I have this UITableView in my iOS chat application, I’m using NSFetchedResultsController to fetch new messages from Coredata and show them to the screen. Insert a new message to the bottom of the uitableview, animate it to this message, and update cells when a message object changes.

lazy var tableView: UITableView = {
    let table = UITableView(frame: .zero, style: .plain)
    
    table.translatesAutoresizingMaskIntoConstraints = false
    
    table.register(UITableViewCell.self, forCellReuseIdentifier: "MessageCell")
    
    table.backgroundColor = .clear
    table.separatorStyle = .none
    
    table.rowHeight = UITableView.automaticDimension
    table.estimatedRowHeight = UITableView.automaticDimension
    
    table.keyboardDismissMode = .interactive
    table.allowsSelection = false
    
    if #available(iOS 15.0, *) {
        table.sectionHeaderTopPadding = 0
    }
    
    return table
}()

var cellHeights = IndexPath: CGFloat

this is the UITableViewDelegate def:

extension ChatViewController: UITableViewDelegate {
    func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        cellHeights[indexPath] = cell.frame.size.height
    }

    func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
        return cellHeights[indexPath] ?? UITableView.automaticDimension
    }
    
    func numberOfSections(in tableView: UITableView) -> Int {
        return self.viewModel.sectionsCount
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.viewModel.numberOfRowsInSection(section: section)
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let messageViewModel = self.viewModel.getViewModel(for: message)
        
        let cell = tableView.dequeueReusableCell(withIdentifier: messageViewModel.identifier, for: indexPath) as! TMMessageCell
        cell.viewModel = messageViewModel
        
        return cell
    }
    
    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        viewModel.headerViewForSection(section: section)
    }
}

This is how I insert/update the table:

func controller(_ controller: NSFetchedResultsController<any NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
    if type == .insert {
        DispatchQueue.main.async {
            self.tableView.beginUpdates()
            self.tableView.insertRows(at: [newIndexPath!], with: .bottom)
            self.tableView.endUpdates()
            
            self.tableView.scrollToRow(at: newIndexPath!,
                                       at: .bottom,
                                       animated: true)
        }
    } else if type == .update {
        DispatchQueue.main.async {
            self.tableView.beginUpdates()
            self.tableView.reloadRows(at: [indexPath!], with: .none)
            self.tableView.endUpdates()
        }
    }
}

when I get messages it works fine(the insert and the scroll), but when I update the cell(right after the scroll) there is a strange scroll in the tableview. Any idea what can be the problem?

I must use the refresh because sometimes I need to change the uitableviewcell because of parameters that I get from the object, so getting the cell and updating it is not an option