Xamarin 自定义 TableViewCell 中的出口为空

Question

I am trying to use a custom UITableViewCell. I am able to get the cell to instantiate, so that it is not null. However, all of the UILabel outlets in the cell are null. Thus, I am getting a null pointer exception.

This is similar to iOS custom TableViewCell class subviews return null and Label in custom cell is null when populating UITableViewController . Nevertheless, neither solutions have solved my problem. They suggest to make sure the identifier matches, which it does. They also tell me to register the cells for reuse, which I also do.

I have made sure that my identifier in the Xib file of the cell matches what I am using.

In my Source class:

public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
{
    tableView.RegisterClassForCellReuse(typeof(BoardListCell), new NSString(BoardListCell.Key));
    var cell = (BoardListCell) tableView.DequeueReusableCell(BoardListCell.Key);
    if (cell == null) 
    {
        var nib = UINib.FromName(BoardListCell.Key, NSBundle.MainBundle);
        cell = (BoardListCell)nib.Instantiate (null, null) [0];
    }

    cell.setData("top", "not top"); //Sample data
    return cell;
}

In my BoardListCell class:

public partial class BoardListCell : UITableViewCell
{
    public static readonly UINib Nib = UINib.FromName ("BoardListCell", NSBundle.MainBundle);
    public static readonly NSString Key = new NSString ("BoardListCell");

    public BoardListCell() : base()
    {

    }

    public BoardListCell (IntPtr handle) : base (handle)
    {

    }

    public void setData(String top, String bottom)
    {
        exp.Text = top;
        playTime.Text = bottom;
    }
}

When I debug, the cell is being created. However, its outlets are null. If I instantiate them in the constructor, I don't get the error, but this obviously defeats the purpose of making prototypes in xcode as it wipes out the layout, etc.

Answer 1

I was having the same issue described above. The solution for me was to remove the call to TableView.RegisterClassForCellReuse(typeof(YourCustomeTableCell), "YourTableCellName");

If you created the Cell in the Xcode designer, there is no need to register the Cell.

Hope this helps anyone still having this issue.