Base view model for Xamarin bindings. Contains helper methods for setting a field and notify the binding.

BaseViewModel.cs

using Foundation;
using System.Runtime.CompilerServices;
using System;

namespace ViewModels
{
    public class BaseViewModel : NSObject
    {
        public event EventHandler PropertyChanged = delegate{};

        protected void SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
        {
            WillChangeValue(propertyName);
            field = value;
            DidChangeValue(propertyName);
            PropertyChanged(this, null);
        }

        protected void SetField<T>(ref T field, T value, string propertyName, params string[] additionalProperties)
        {
            foreach (var prop in additionalProperties)
            {
                WillChangeValue(prop); 
            }
            WillChangeValue(propertyName);
            field = value;
            DidChangeValue(propertyName);
            foreach (var prop in additionalProperties)
            {
                DidChangeValue(prop);
            }
            PropertyChanged(this, null);
        }
    }
    
    public class DemoViewModel : BaseViewModel
    {
        private string _str;

        [Export("Str")]
        public string Str
        {
            get { return _str; }
            set { SetField(ref _str, value); }
        }

        private string _strWithOtherBindings;

        [Export("StrWithOtherBindings")]
        public string StrWithOtherBindings
        {
            get { return _strWithOtherBindings; }
            set { SetField(ref _strWithOtherBindings, value, "StrWithOtherBindings", "OtherBinding"); }
        }
    }
}