How to underline label with underline effect in Xamarin Forms?

Question

I followed this tutorial to create underline effect. However, when my page starts it breaks without exception being caught. Has anyone managed to create underline effect? Here is a code:

UnderlineEffect.cs:

namespace XX.CustomForms
{
    public class UnderlineEffect : RoutingEffect
    {
        public const string EffectNamespace = "XX.CustomForms";

        public UnderlineEffect() : base($"{EffectNamespace}.{nameof(UnderlineEffect)}")
        {
        }
    }
}

UnderlineLabel_Droid.cs:

[assembly: ResolutionGroupName(UnderlineEffect.EffectNamespace)]
[assembly: ExportEffect(typeof(UnderlineEffect), nameof(UnderlineEffect))]
namespace XX.Droid.Renderers
{
    public class UnderlineEffect : PlatformEffect
    {
        protected override void OnAttached()
        {
            SetUnderline(true);
        }

        protected override void OnDetached()
        {
            SetUnderline(false);
        }

        protected override void OnElementPropertyChanged(System.ComponentModel.PropertyChangedEventArgs args)
        {
            base.OnElementPropertyChanged(args);

            if (args.PropertyName == Label.TextProperty.PropertyName || args.PropertyName == Label.FormattedTextProperty.PropertyName)
            {
                SetUnderline(true);
            }
        }

        private void SetUnderline(bool underlined)
        {
            try
            {
                var textView = (TextView)Control;
                if (underlined)
                {
                    textView.PaintFlags |= PaintFlags.UnderlineText;
                }
                else
                {
                    textView.PaintFlags &= ~PaintFlags.UnderlineText;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Cannot underline Label. Error: ", ex.Message);
            }
        }
    }
}

And my xaml:

    xmlns:custom="clr-namespace:XX.CustomForms;assembly=XX"

    <Label Text="Privacy Notice" HorizontalTextAlignment="Center" >
        <Label.Effects>
            <custom:UnderlineEffect />
        </Label.Effects>
    </Label>

Answer 1

Xamarin Forms added a TextDecorations property to Labels. Update to Xamarin Forms 3.3.0+ and just set:

C#

Label label = new Label {
    TextDecorations = TextDecorations.Underline
}

XAML

<Label TextDecorations="Underline"/>

Docs Link

Be aware that there was a bug on iOS when an underlined Label is in a ListView. Looks like it has been fixed and released in 3.5.0. I am still using a custom renderer on iOS for now until I am ready to update to the latest version.

GitHub issue

So continue using the iOS effect if you have not updated to XF 3.5.0 yet.

Answer 2

The lengths some people are going to to get underlined text in Xamarin is insane. Here's a way to do it without a thousand line custom renderer. The negative margin trick came from this guy.

<StackLayout HorizontalOptions="Start">
    <Label Text="Underlined Text" />
    <BoxView HeightRequest="1" BackgroundColor="Purple" HorizontalOptions="FillAndExpand" Margin="0,-7,0,0" />
</StackLayout>

Answer 3

Use TextDecorations property in Label class.

<Label Text="Underlined Text" TextDecorations="Underline"/>