how to change default color when switch is "on"(blue to green) in forms xamarin. In ios default it is GReen but in android it is blue

wirth this code i am getting swith in blue color when it "on". i want to change it to green.

using Xamarin.Forms;

namespace swithcasedemo
{
    public class MyPage : ContentPage
    {
        public MyPage ()
        {
            Content = new StackLayout { 
                Children = {
                    new Label { Text = "Hello ContentPage",
                        HorizontalOptions=LayoutOptions.Center,
                        VerticalOptions=LayoutOptions.CenterAndExpand
                    },
                    new Switch{
                        HorizontalOptions=LayoutOptions.Center,
                        VerticalOptions=LayoutOptions.CenterAndExpand,


                    },


                }
            };
        }
    }
}