Annotation (Grid line ) for the DateTimeContinuousAxis is not visualized on iOS. It works as expected on Android.

Add grid line annotation for the datetime axes. the grid lines are not visualized on iOS. 

<telerikChart:RadCartesianChart x:Name="chart">
    <telerikChart:RadCartesianChart.BindingContext>
        <local:ViewModel />
    </telerikChart:RadCartesianChart.BindingContext>
    <telerikChart:RadCartesianChart.HorizontalAxis>
        <telerikChart:DateTimeContinuousAxis LabelFitMode="Rotate" 
                                                x:Name="horizontal"/>
    </telerikChart:RadCartesianChart.HorizontalAxis>
    <telerikChart:RadCartesianChart.VerticalAxis>
        <telerikChart:NumericalAxis />
    </telerikChart:RadCartesianChart.VerticalAxis>
    <telerikChart:RadCartesianChart.Series>            
        <telerikChart:SplineSeries ValueBinding="Value"
                                    CategoryBinding="Date"
                                    ItemsSource="{Binding Data}"
                                    ShowLabels="True"
                                    />
    </telerikChart:RadCartesianChart.Series>
    <telerikChart:RadCartesianChart.Annotations>
        <telerikChart:CartesianGridLineAnnotation Stroke="#0E72F6" 
                                                StrokeThickness="2"
                                                Value="{Binding Threshold}"
                                                Axis="{x:Reference horizontal}">
            <telerikChart:CartesianGridLineAnnotation.DashArray>
                <x:Array Type="{x:Type x:Double}">
                    <x:Double>4.0</x:Double>
                    <x:Double>2.0</x:Double>
                </x:Array>
            </telerikChart:CartesianGridLineAnnotation.DashArray>
        </telerikChart:CartesianGridLineAnnotation>
    </telerikChart:RadCartesianChart.Annotations>
</telerikChart:RadCartesianChart>  

Put several Pie charts in a StackPanel and set the WidthRequest and HeightRequest to let's say 60. You will notice that the circular pie itlsef appears much smaller than the expected 60. In Android and Windows Phone it appears as expected.

Expose API for series items label formatting in the chart.

NSRangeException is thrown when second series has more items than the first one on iOS.

Available in the R3 2018 SP release.

Add a title for the horizontal and vertical axis.

When having the following code on a button click 

private void Button_Clicked(object sender, System.EventArgs e)
{
       this.chart.Zoom = new Size();
}

The chart zoom is reset first time, but when zooming again and pressing the button, the zoom level does not reset. You have to pan the chart, then zoom reset works. 

This code resets the zoom:

private void OnResetZoomClicked(object sender, EventArgs e)
{
	this.chart.Zoom = new Size(1, 1); // This line is added as a workaround to reset the Zoom level
	this.chart.Zoom = new Size();
}

The Chart should be able to display callout annotations.

When the chart has a lot of data, you may not necessarily want to show it all when the chart initially appears, but you may want to show the chart in a semi-zoomed state. Therefore, there should be properties which govern the ranges by which the chart should appear zoomed initially. So, the end-user should be able to zoom in/out starting from this state and then return to the same state if necessary (avoiding getting the whole data if he zooms out too much).

Request for ranged series types.

Here's an example of such a series type from UI for WPF http://docs.telerik.com/devtools/wpf/controls/radchartview/series/cartesianchart-series/bar-series/rangebarseries 

Request for polar axis series types:

- Radar Series
- Phasor
- Polar

If series' ItemsSource is a collection of objects implementing INotifyPropertyChanged, the chart should be automatically updated when an item is updated.

Available in the R3 2018 SP release.

When you declare a specific CalendarAppointmentsStyle and assign it to the AppointmentsStyle property of the RadCalendar - it is not respected. However, if you try to set it in the NativeControlLoaded event, the changes are correctly applied. 

Available in minor release 2018.1.405. It will also be available in the R2 2018 release.