mvvm Failed to create target binding for binding - data-binding

Question

I've read a lot of solutions on the current problem but none of them worked and I cannot
figure out how to do the following:
the converter
public class HexToUIColorValueConverter : MvxValueConverter<int, UIColor>
{
protected override UIColor Convert(int value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return UIColor.FromRGB(
(((float)((value & 0xFF0000) >> 16)) / 255.0f),
(((float)((value & 0xFF00) >> 8)) / 255.0f),
(((float)(value & 0xFF)) / 255.0f)
);
}
}
the binding
public SubtitleDetailViewCell(IntPtr handle)
: base(handle)
{
Initialize();
this.DelayBind(() =>
{
Accessory = UITableViewCellAccessory.DisclosureIndicator;
var set = this.CreateBindingSet<SubtitleDetailViewCell, ObservationMedicale>();
set.Bind(MainLbl).To(observation => observation.Texte).WithConversion(new ByteArrayToStringValueConverter(), null);
set.Bind(LeftDetailLbl).To(observation => observation.SaisieLe).WithConversion(new StringFormatValueConverter(), "d MMM, HH:mm");
set.Bind(RightDetailImgLbl.Label).SourceDescribed("PraticienNom + ' ' + PraticienPrenom");
set.Bind(Label.Color).To(observation => observation.ObsCategorieCouleur).WithConversion(new HexToUIColorValueConverter(), null);
set.Apply();
});
}
the binded object
using System;
using System.Drawing;
using MonoTouch.CoreGraphics;
using MonoTouch.Foundation;
using MonoTouch.UIKit;
namespace Next.Client.Application.iOS.Views.UI
{
[Register("CellLabelView")]
public class CellLabelView : UIView
{
public UIColor Color { get; set; }
public CellLabelView()
{
Initialize();
}
public CellLabelView(IntPtr handle)
: base(handle)
{
}
public CellLabelView(RectangleF bounds)
: base(bounds)
{
Initialize();
}
void Initialize()
{
BackgroundColor = UIColor.Clear;
Opaque = false;
}
public override void Draw(RectangleF rect)
{
base.Draw(rect);
// get graphics context
using (CGContext gc = UIGraphics.GetCurrentContext())
{
// set up drawing attributes
gc.SetLineWidth(1);
_color.SetFill();
UIColor.Clear.SetStroke();
//create geometry
var path = new CGPath();
path.AddLines(new PointF[]{
new PointF (0, 0),
new PointF (0, 8),
new PointF (4, 4),
new PointF (8, 8),
new PointF (8, 0)
});
path.CloseSubpath();
//add geometry to graphics context and draw it
gc.AddPath(path);
gc.DrawPath(CGPathDrawingMode.FillStroke);
}
}
}
}
I don't understand how it fails to bind the color, the SET method on CellLabel is never called and so my Color in the Draw() method isn't a valid object.

Answer 1

Currently you are trying to bind the color object directly - rather than trying to bind the color property on your label.
Try:
set.Bind(Label).For(l => l.Color).To(observation => observation.ObsCategorieCouleur).WithConversion(new HexToUIColorValueConverter(), null);
For a breakdown on this fluent syntax, including For, see https://github.com/MvvmCross/MvvmCross/wiki/Databinding#fluent
Beyond this, you probably also should try to change your Color auto-property to a property with some code inside that requests a redraw via Invalidate whenever the color is changed.