title: 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
body: <p>wirth this code i am getting swith in blue color when it "on". i want to change it to green.</p>
  
  <pre><code>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,
  
  
                      },
  
  
                  }
              };
          }
      }
  }
  </code></pre>