Essential Studio for Xamarin.Forms
Spline Area Chart & Graph

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:ChartExample"
             xmlns:chart="clr-namespace:Syncfusion.SfChart.XForms;assembly=Syncfusion.SfChart.XForms"
             x:Class="ChartExample.MainPage">

    <ContentPage.BindingContext>
        <local:ViewModel/>
    </ContentPage.BindingContext>

    <chart:SfChart>

        <chart:SfChart.PrimaryAxis>
            <chart:CategoryAxis/>
        </chart:SfChart.PrimaryAxis>

        <chart:SfChart.SecondaryAxis>
            <chart:NumericalAxis/>
        </chart:SfChart.SecondaryAxis>

        <chart:SplineAreaSeries ItemsSource="{Binding Data}" XBindingPath="Month" YBindingPath="Target"/>

    </chart:SfChart>

</ContentPage>

public class Model
{
    public string Month { get; set; }

    public double Target { get; set; }

    public Model(string xValue, double yValue)
    {
        Month = xValue;
        Target = yValue;
    }
}

public class ViewModel
{
    public ObservableCollection<Model> Data { get; set; }

    public ViewModel()
    {
        Data = new ObservableCollection<Model>()
        {
            new Model("Jan", 50),
            new Model("Feb", 70),
            new Model("Mar", 65),
            new Model("Apr", 57),
            new Model("May", 48), 
        };
    }
}