public override void ViewDidLoad() {
 base.ViewDidLoad();
  chart.ItemsSource = new LineMarkerViewModel().Items;
 // initialize series elements and set the binding to variables of
 // ChartPoint
 chart.ChartType = ChartType.Line;
 chart.BindingX = "Date";
 ChartSeries inputSeries = new ChartSeries();
 ChartSeries outputSeries = new ChartSeries();
 inputSeries.SeriesName = "Input";
 inputSeries.Binding = "Input";
 outputSeries.SeriesName = "Output";
 outputSeries.Binding = "Output";
 chart.Series.Add(inputSeries);
 chart.Series.Add(outputSeries);

 initMarker();
 chart.Layers.Add(lineMarker);
}

private void initMarker() {
 lineMarker = new C1LineMarker();
 lineMarker.DragContent = true;
 UIView view = new UIView(new CGRect(0, 0, 110, 70));
 xLabel = new UILabel(new CGRect(5, 5, 110, 20));
 view.Add(xLabel);
 view.BackgroundColor = UIColor.LightGray;
 for (int index = 0; index < chart.Series.Count; index++) {
  var series = chart.Series[index];
  var fill = ((IChart) chart).GetColor(index);
  UILabel yLabel = new UILabel(new CGRect(5, 25 + 20 * index, 110, 20));
  yLabels.Add(yLabel);
  view.Add(yLabel);
 }
 lineMarker.Content = view;
 lineMarker.PositionChanged += LineMarker_PositionChanged;
}

private void LineMarker_PositionChanged(object sender, PositionChangedArgs e) {
 if (chart != null) {
  var info = chart.HitTest(new CGPoint(e.Position.X, double.NaN));
  int pointIndex = info.PointIndex;
  xLabel.Text = string.Format("{0:MM-dd}", info.X);

  for (int index = 0; index < chart.Series.Count; index++) {
   var series = chart.Series[index];
   var value = series.GetValues(0)[pointIndex];

   var fill = (int)((IChart) chart).GetColor(index);
   string content = string.Format("{0} = {1}", series.SeriesName, string.Format("{0:f0}", value));
   UILabel yLabel = yLabels[index];
   yLabel.Text = content;
  }
 }
}
public class LineMarkerViewModel
   {
      const int Count = 300;
      Random rnd = new Random();

      public List<LineMarkerSampleDataItem> Items
      {
       get
       {
          List<LineMarkerSampleDataItem> items = new List<LineMarkerSampleDataItem>();
          DateTime date = new DateTime(2016, 1, 1);
          for (var i = 0; i < Count; i++)
          {
          var item = new LineMarkerSampleDataItem()
          {
          Date = date.AddDays(i),
          Input = rnd.Next(10, 20),
          Output = rnd.Next(0, 10)
          };
          items.Add(item);
          }
          return items;
                }
            }
            public List<string> LineType
            {
                get
                {
                    return Enum.GetNames(typeof(LineMarkerLines)).ToList();
                }
            }
            public List<string> LineMarkerInteraction
            {
                get
                {
                    return Enum.GetNames(typeof(LineMarkerInteraction)).ToList();
                }
            }
        }
        public class LineMarkerSampleDataItem
        {
            public int Input { get; set; }
            public int Output { get; set; }
            public DateTime Date { get; set; }
        }
    }