Create infinite scroll effect by inserting new rows

Question

I have a UITableView that lists out data from an api.

Currently those responses are batched in groups of 50 items.

To support 'infinite scrolling' I currently do something like this

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    if indexPath.row == items.count - 1 && !isPaginating {
        requestNextPage()
    }
}

When requestNextPage completes, I update the array on my view model and then call

func reloadTableView() -> Void {
    DispatchQueue.main.async {
        self.activity.stopAnimating()
        self.tableView?.reloadData()
    }
}

which essentially reloads the table, rendering the new rows added to my array by requestNextPage.

I don't like this approach as it causes the whole table to be reloaded and feels a bit......clunky.

I was thinking perhaps it is better to do this with insertRowsAtIndexPaths but I am not sure how I can achieve this.

I tried something like

   var indexPaths = [IndexPath]()

        for i in self.items.count...self.items.count + feed.count {
            indexPaths.append(IndexPath(row: i, section: 0))
        }

        self.insertNewRows?(indexPaths)

Which I hoped would take the existing row count items.count and add my new rows feed.count and then let me call insertNewRows which essentially triggers this in my view

func insertRows(_ indexPaths: [IndexPath]) {
    tableView?.beginUpdates()
    tableView?.insertRows(at: indexPaths, with: .fade)
    tableView?.endUpdates()
}

Is it possible to create an infinite scroll effect in this manor? My current approach triggers an exception

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'attempt to insert row 50 into section 0, but there are only 50 rows in section 0 after the update'

I am using Swift, so Objective C answers are proving difficult to follow, and I would prefer not to install a 3rd party library to handle this.

The 'duplicate' question also recommend a lib that has not been updated in 7 years.

Create infinite scroll effect by inserting new rows

0 Answers0