MvxConvertingTargetBinding for Android navigation views which have IMenu members

BottomNavigationItemSelectedTargetBinding.cs

using Android.Support.Design.Widget;
using MvvmCross.Binding;
using MvvmCross.Binding.Bindings.Target;
using System;
using System.Windows.Input;

namespace YourNamespace
{
    public class NavigationItemSelectedTargetBinding : MvxConvertingTargetBinding
    {
        ICommand _command;
        BottomNavigationView _target;

        public NavigationItemSelectedTargetBinding(BottomNavigationView target)
            : base(target)
        {
        }

        public override Type TargetType => typeof(BottomNavigationView);

        public override MvxBindingMode DefaultMode => MvxBindingMode.OneWay;

        protected override void SetValueImpl(object target, object value)
        {
            _target = target as BottomNavigationView;

            _command = value as ICommand;

            _target.NavigationItemSelected += Target_NavigationItemSelected;
        }

        // TODO :: Don't use the title as the command parameter -- it is subject to locale issues
        void Target_NavigationItemSelected(object sender, BottomNavigationView.NavigationItemSelectedEventArgs e)
            => _command.Execute(e.Item.TitleFormatted.ToString());

        protected override void Dispose(bool isDisposing)
        {
            base.Dispose(isDisposing);

            _target.NavigationItemSelected -= Target_NavigationItemSelected;
        }
    }
}

This is an example for BottomNavigationView, but a similar TargetBinding should be largely the same for other Android NavigationViews. Implementation is the same as ever.

Binding statement:

yourBindingSet.Bind(YourNavigationView).For("YourBindingKey").To(vm => vm.YourCommand);

Command + navigation helpers:

IMvxCommand _yourCommand;
public IMvxCommand YourCommand =>
        _yourCommand ?? (_yourCommand = new MvxCommand<string>(Navigate));

void Navigate(string navigationKey)
{
    if (navigationKey.Equals("exampleOne", StringComparison.OrdinalIgnoreCase))
        GoToExampleOne();

    if (navigationKey.Equals("exampleTwo", StringComparison.OrdinalIgnoreCase))
        GoToExampleTwo();
}

void GoToExampleOne() => ShowViewModel<ExampleOneViewModel>();

void GoToExampleTwo() => ShowViewModel<ExampleTwoViewModel>();

Setup.cs:

registry.RegisterCustomBindingFactory<BottomNavigationView>("YourBindingKey", view => new BottomNavigationItemSelectedTargetBinding(view));