How to scroll UITableView to a row *safely*?

Question

Sometimes when I tried to scroll a tableview to a row, I can unexpectedly supply a nonexistent section/row. And then the app will crash.

self.tableView.scrollToRow(at: IndexPath(row: targetRow, section: targetSection), at: UITableViewScrollPosition.bottom, animated: true);

How can I make this scrolling process crash-safe? I mean, if I do supply a nonexistent section/row, I want UITableView just ignore it. Or how can I check whether a section/row is exist or not within a UITableView before I do the scroll? Thanks.

Answer 1

Use this UITableView extension to check whether a Indexpath is valid.

extension UITableView
{
    func indexPathExists(indexPath:IndexPath) -> Bool {
        if indexPath.section >= self.numberOfSections {
            return false
        }
        if indexPath.row >= self.numberOfRows(inSection: indexPath.section) {
            return false
        }
        return true
    }
}

Use like this

var targetRowIndexPath = IndexPath(row: 0, section: 0)
if table.indexPathExists(indexPath: targetRowIndexPath)
{
  table.scrollToRow(at: targetRowIndexPath, at: .bottom, animated: true)
}

Answer 2

Try this --

let indexPath = IndexPath(row: targetRow, section: targetSection)
if let _ = self.tableView.cellForRow(at: indexPath) {
 self.tableView.scrollToRow(at: indexPath, at: UITableViewScrollPosition.bottom, animated: true)
}