iOS custom TableViewCell class subviews return null

Question

I use Xamarin iOS designer to design custom TableViewCell class for my TableView. But all cell subviews properties (outlets) return null except cell itself.

My custom cell class:

partial class VehiclesTableCell : UITableViewCell
{
    public VehiclesTableCell(IntPtr handle) : base(handle) { }

    public void UpdateCell(string licensePlate) {
        licensePlateLabel.Text = licensePlate; //hit the null reference exception for licensePlateLabel 
    }
}

Generated partial class:

[Register ("VehiclesTableCell")]
partial class VehiclesTableCell
{
    [Outlet]
    [GeneratedCode ("iOS Designer", "1.0")]
    UILabel licensePlateLabel { get; set; }

    void ReleaseDesignerOutlets ()
    {
        if (licensePlateLabel != null) {
            licensePlateLabel.Dispose ();
            licensePlateLabel = null;
        }
    }
}

And GetCell of my Table Source class:

public class VehiclesTableSource : UITableViewSource
{
    public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath) {

        // Dequeueing the reuse cell
        var cell = (VehiclesTableCell)tableView.DequeueReusableCell(new NSString(typeof(VehiclesTableCell).Name));

        // Set cell properties
        cell.UpdateCell(LicensePlate);

        // Return the cell with populated data
        return cell;
    }
}

As we see genereted code has an outlet for licensePlate so why is its property null? Is storyboard not supposed to instantiate all of its subviews automatically? At least its happening in all other situations.

enter image description here

You should create cell if it is null in GetCell method. Check this in that they show how to create cell if it is null. — Janak Nirmal
Cell is not null, only its properties Labels, ImageViews etc — Arvis
Just a thought, check IBOutlets connections, as we are not using Xamarin studio can't tell much on that Check this too. — Janak Nirmal
@JanakNirmal, with the custom cell class registered for TableView in controller, the cell can be dequeued in the GetCell method of the UITableViewSource without the need for the extra null check. TableView.RegisterClassForCellReuse (typeof(MyCell), MyCellId); — Arvis
@Tomzie, yes i do. Just eliminate unnecessary registration of custom cell by removing line: TableView.RegisterClassForCellReuse(typeof(VehiclesTableCell), new NSString("VehicleCell")); in ViewDidLoad methode. — Arvis

Vera Rivotti Vera Rivotti · Accepted Answer · 2015-07-15T17:54:53

I was having the same problem with my custom TableViewCell. I found out the issue was with TableView.RegisterClassForCellReuse (typeof(MyCell), MyCellId). I had to change it to TableView.RegisterNibForCellReuse(UINib.FromName("MyCell", NSBundle.MainBundle), MyCellId) in order to get my .xib loaded.

iOS custom TableViewCell class subviews return null

3 Answers