LocalizerTranslateExtension.cs

using System;
using System.Runtime.CompilerServices;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace SalesHub.Framework.Localization
{
    [ContentProperty("Text")]
    public class LocalizerTranslateExtension : BindableObject, IMarkupExtension<BindingBase>
    {
        public string Text { get; set; }
       // public ILocalizer Localizer { get; set; }

        public static readonly BindableProperty LocalizerProperty = BindableProperty.Create(nameof(Localizer), typeof(ILocalizer), typeof(ILocalizer), null);
        public ILocalizer Localizer
        {
            get { return (ILocalizer) GetValue(LocalizerProperty); }
            set { SetValue(LocalizerProperty, value); }
        }

        object IMarkupExtension.ProvideValue(IServiceProvider serviceProvider)
        {
            return ProvideValue(serviceProvider);
        }

        public BindingBase ProvideValue(IServiceProvider serviceProvider)
        {
            var binding = new Binding
            {
                Mode = BindingMode.TwoWay,
                Path = $"[{Text}]",
                Source = this,
            };
            return binding;
        }

        protected override void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            base.OnPropertyChanged(propertyName);

            if(propertyName == LocalizerProperty.PropertyName)
            {
                Text = Localizer.GetTranslation(Text);
            }
        }
    }
}