UITableView子类一些未调用的重写方法

Question

I have subclassed UITableView with the required methods overridden in the subclass to populate the table view. However while NumberOfSections is called, NumberOfRowsInSection is not called.

The code below is from a Xamarin project but this is no different to its equivalent native version with slight differences in method names.

partial class ShootsTable : UITableView, IUISearchResultsUpdating, IUISearchBarDelegate
{
    public bool History { get; set; }
    public UIViewController Parent { get; set; }

    private Bootleg.API.Event[] Events { get; set; }
    private List<nint> ExpandedSections { get; }

    public ShootsTable (IntPtr handle) : base (handle)
    {
        ExpandedSections = new List<nint> ();
        SetEvents();
    }

    private void SetEvents()
    {
        if (History) {
            Events = AppDelegate.Api.GetShootHistory ().ToArray();
        } else {
            Events = AppDelegate.Api.MyEvents.ToArray();
        }
    }

    private void AddRefreshControl()
    {
        var refreshControl = new UIRefreshControl ();
        refreshControl.AttributedTitle = new NSAttributedString ("Pull to refresh");
        refreshControl.AddTarget (async delegate(object sender, EventArgs e) {
            await AppDelegate.Api.RefreshEvents();
            SetEvents();
            ReloadData();
            refreshControl.EndRefreshing();
        }, UIControlEvent.ValueChanged);

        AddSubview (refreshControl);
    }

    private void AddSearchControl()
    {
        var searchControl = new UISearchController (Parent);
        searchControl.SearchResultsUpdater = this;
        searchControl.SearchBar.Delegate = this;
        TableHeaderView = searchControl.SearchBar;
    }

    public void UpdateSearchResultsForSearchController (UISearchController searchController)
    {
        SetEvents ();
        Events = Events.Where (e => e.name.Contains (searchController.SearchBar.Text)).ToArray ();
        ReloadData ();
    }

    public override nint NumberOfSections ()
    {
        if (Events != null && Events.Length > 0)
        {
            SeparatorStyle = UITableViewCellSeparatorStyle.SingleLine;
            return Events.Length;
        }

        var label = new UILabel (new CGRect (Bounds.X, Bounds.Y, Bounds.Size.Width, Bounds.Size.Height));
        label.Text = History ? "You have not contributed to any shoots yet." : "No shoots available.";
        label.Lines = 2;
        label.TextAlignment = UITextAlignment.Center;

        BackgroundView = label;
        SeparatorStyle = UITableViewCellSeparatorStyle.None;

        return 0;
    }

    public override nint NumberOfRowsInSection (nint section)
    {
        var e = Events[section];

        if (e.group == null)
        {
            return 1;
        }

        return ExpandedSections.Contains (section) ? e.events.Count : 0;
    }

    [Export ("tableView:heightForHeaderInSection:")]
    public System.nfloat GetHeightForHeader (UIKit.UITableView tableView, System.nint section)
    {
        return Events [section].group == null ? 0 : tableView.SectionHeaderHeight;
    }

    [Export ("tableView:viewForHeaderInSection:")]
    public UIKit.UIView GetViewForHeader (UIKit.UITableView tableView, System.nint section)
    {
        var e = Events [section];

        if (e.group == null)
        {
            return null;
        }

        var cell = (ShootGroupCell) tableView.DequeueReusableCell (ShootGroupCell.Key);

        cell.Event = e;

        cell.AddGestureRecognizer (new UITapGestureRecognizer(() => {
            if (ExpandedSections.Contains(section))
            {
                ExpandedSections.Remove(section);
                tableView.ReloadSections(new NSIndexSet((nuint) section), UITableViewRowAnimation.Automatic);
            } else {
                ExpandedSections.Add(section);
                tableView.ReloadSections(new NSIndexSet((nuint) section), UITableViewRowAnimation.Automatic);
            }
        }));

        return cell.ContentView;
    }

    public override UITableViewCell CellAt (NSIndexPath ns)
    {
        var e = Events[ns.Section];

        e = e.group == null ? e : e.events[ns.Row];

        if (History) {
            var cell = (ShootCell)DequeueReusableCell (ShootCell.Key);
            cell.Event = e;
            cell.Parent = Parent;
            return cell;
        } else {
            var cell = (ShootJoinCell) DequeueReusableCell (ShootJoinCell.Key);
            cell.Event = e;
            return cell;
        }
    }

    [Export ("tableView:heightForRowAtIndexPath:")]
    public System.nfloat GetHeightForRow (UIKit.UITableView tableView, Foundation.NSIndexPath indexPath)
    {
        return Events [indexPath.Section].group == null || ExpandedSections.Contains (indexPath.Section) ? tableView.RowHeight : 0;
    }

    [Export ("tableView:didSelectRowAtIndexPath:")]
    public async void RowSelected (UIKit.UITableView tableView, Foundation.NSIndexPath indexPath)
    {
        if (!History)
        {
            var e = Events [indexPath.Section];

            if (e.group != null) {
                e = e.events [indexPath.Row];
            }

            MBHUDView.HudWithBody ("Connecting Event...", MBAlertViewHUDType.ActivityIndicator, 0, true);
            await AppDelegate.Api.ConnectToEvent (e, false);
            MBHUDView.DismissCurrentHUD ();

            if (AppDelegate.Api.CurrentEvent.id != e.id)
            {
                var alert = UIAlertController.Create ("Confirm", "This event requires you to confirm you wish to join.", UIAlertControllerStyle.Alert);
                alert.AddAction(UIAlertAction.Create("Join", UIAlertActionStyle.Default, async delegate {
                    MBHUDView.HudWithBody ("Connecting Event...", MBAlertViewHUDType.ActivityIndicator, 0, true);
                    await AppDelegate.Api.ConnectToEvent (e, true);
                    MBHUDView.DismissCurrentHUD ();

                    e = AppDelegate.Api.CurrentEvent;

                    DialogHelper.PermissionsDialog (e, delegate {
                        Parent.PerformSegue("phasesSegue", tableView);
                    }, null, Parent);
                }));
                alert.AddAction(UIAlertAction.Create("Cancel", UIAlertActionStyle.Cancel, null));

                Parent.PresentViewController (alert, true, null);
            }
            else
            {
                e = AppDelegate.Api.CurrentEvent;

                DialogHelper.PermissionsDialog (e, delegate {
                    Parent.PerformSegue("phasesSegue", tableView);
                }, null, Parent);
            }
        }
    }

Now I have been looking at several possible solutions however it seems quite uncommon to sub-class UITableView with the majority of solutions simply being not setting the delegate or data source properly. I have also seen a SO solution to this issue simply being the TableView not being in view and therefore the delegate methods do not need to be called however this is not the case.

I do not need to set delegate methods as I am subclassing UITableView itself and it is sufficient to just override the built in methods. In the storyboard I set the class to my custom class ShootsTable .

Does anyone have any ideas?

Thanks in advance.

Answer 1

This appears to be a bug. Not sure what level (Xamarin or iOS) it is at but as soon as this is changed back to a IUITableViewDataSource implementation it works.

I will report this to Xamarin and see what comes back.