How to change Picker underline color in Xamarin Forms

Question

I am using Picker control, by default it shows White underline color on Black screen.

But I need to have white screen background color, then Picker underline is not displaying at all. See below image:

So how can I change Picker underline color

This is my Picker

 <Picker TitleColor="Black" Title="--Select--" />

Answer 1

you could use custom renderer to achieve it：

for Android:

[assembly: ExportRenderer(typeof(Picker), typeof(CustomPickerRenderer))]
namespace App18.Droid
{
  public class CustomPickerRenderer : PickerRenderer
   {
      private Context context;
      public CustomPickerRenderer(Context context) : base(context)
       {
        this.context = context;
       }

      protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
       {
        base.OnElementChanged(e);
        if (Control == null || e.NewElement == null) return;
        //for example ,change the line to red:
        if (Build.VERSION.SdkInt >= BuildVersionCodes.Lollipop)
            Control.BackgroundTintList = ColorStateList.ValueOf(Color.Red);
        else
            Control.Background.SetColorFilter(Color.Red, PorterDuff.Mode.SrcAtop);
       }
   }
}

for iOS:

[assembly: ExportRenderer(typeof(Picker), typeof(CustomPickerRenderer))]
namespace App18.iOS
{
  public class CustomPickerRenderer : PickerRenderer
   {

    protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
    {
        base.OnElementChanged(e);

        if (Control == null || e.NewElement == null)
            return; 
        Control.Layer.BorderWidth = 1;
        Control.Layer.BorderColor = Color.Red.ToCGColor();
    }
   }
}