public override UITableViewCell GetCell(UITableView tableView, Foundation.NSIndexPath indexPath)
{
// We will need a cancellationTokenSource so we can cancel the async call if the view moves back on screen
// while text is already being loaded. Without this, if a view is loading some text, but the view moves off
// and back on screen, the new load may take less time than the old load and then the old load will
// overwrite the new text load and the wrong data will be displayed. So we will c ancel any async task on a
// recycled view before loading the new text.
CancellationTokenSource cts;
TableViewCellWithCTS cell = tableView.DequeueReusableCell(CellIdentifier) as TableViewCellWithCTS;
if (cell == null)
{
cell = new TableViewCellWithCTS(UITableViewCellStyle.Default, CellIdentifier);
}
else
{
// If cell exists, cancel any pending async text loading for this cell
// by calling cts.Cancel();
cts = cell.Cts;
// If cancellation has not already been requested, cancel the async task
if (!cts.IsCancellationRequested)
{
cts.Cancel();
}
}
cell.TextLabel.Text = "Placeholder";
// Create new CancellationTokenSource for this view's async call
cts = new CancellationTokenSource();
// Add to the Cts property of the cell
cell.Cts = cts;
// Get the cancellation token to pass into the async method
var ct = cts.Token;
Task.Run(async() =>
{
try
{
string text = await GetTextAsync(indexPath.Row, ct);
InvokeOnMainThread(() => {
cell.TextLabel.Text = text;
});
}
catch (System.OperationCanceledException ex)
{
Console.WriteLine($"Text load cancelled: {ex.Message}");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}, ct);
return(cell);
}
public override UITableViewCell GetCell(UITableView tableView, Foundation.NSIndexPath indexPath)
{
TableViewCellWithCTS cell = tableView.DequeueReusableCell(CellIdentifier) as TableViewCellWithCTS;
if (cell == null)
{
cell = new TableViewCellWithCTS(UITableViewCellStyle.Default, CellIdentifier);
}
string text = GetTextAsync(indexPath.Row).Result;
cell.TextLabel.Text = text;
return(cell);
}