Binding not working with MVVM in xamarin form. No property, bindable property, or event found for 'ItemSelected',

I am trying to bind my ListView ItemSelected with with my ViewModel using MVVM in xamarin. For some I am getting a compile time error " No property, bindable property, or event found for 'ItemSelected', or mismatching type between value and property. Scheduler" I have binded my ViewModel in the UI code Behind. Below is my code

UI Code Behind

  [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class ClientPage : ContentPage
    {
        private ClientViewModel viewModel {get;}
        public ClientPage()
        {
            InitializeComponent();
            BindingContext = viewModel = new ClientViewModel();
        }
    }

ViewModel

 public class ClientViewModel : BaseViewModel
    {
 public ObservableCollection<Client> Clients { get; set; }
        private Client _SelectedItem { get; set; }
        public Client SelectedClient
        {
            get
            {
                return _SelectedItem;
            }
            set
            {
                _SelectedItem = value;
                Task.Run(async () => await ShowClientDetailModal(_SelectedItem));
            }
        }
    }

UI

 <StackLayout>
        <ListView x:Name="ClientListView"
                  ItemsSource="{Binding Clients}"
                  VerticalOptions="FillAndExpand"
                  HasUnevenRows="true"
                  RefreshCommand="{Binding LoadClientsCommand}"
                  IsPullToRefreshEnabled="True"
                  IsRefreshing="{Binding IsBusy, Mode=OneWay}"
                  CachingStrategy="RecycleElement"
                  ItemSelected="{Binding SelectedClient}">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <ViewCell.ContextActions>
                            <MenuItem Clicked="OnDelete_Clicked" Text="Delete" CommandParameter="{Binding .}"/>
                        </ViewCell.ContextActions>
                        <StackLayout Padding="10">
                                   <Label Text="{Binding FullName}"
                                   d:Text="{Binding .}"
                                   LineBreakMode="NoWrap"
                                   Style="{DynamicResource ListItemTextStyle}" />
                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </StackLayout>

ItemSelected is an event, not a bindable property what you are looking for is a behaviour that converts your Event to a Command

If you check the Microsoft documents you can find one here: https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/behaviors/reusable/event-to-command-behavior

Behavior:

  public class EventToCommandBehavior : BehaviorBase<View>
{
Delegate eventHandler;
public static readonly BindableProperty EventNameProperty = BindableProperty.Create ("EventName", typeof(string), typeof(EventToCommandBehavior), null, propertyChanged: OnEventNameChanged);
public static readonly BindableProperty CommandProperty = BindableProperty.Create ("Command", typeof(ICommand), typeof(EventToCommandBehavior), null);
public static readonly BindableProperty CommandParameterProperty = BindableProperty.Create ("CommandParameter", typeof(object), typeof(EventToCommandBehavior), null);
public static readonly BindableProperty InputConverterProperty = BindableProperty.Create ("Converter", typeof(IValueConverter), typeof(EventToCommandBehavior), null);
public string EventName {
get { return (string)GetValue (EventNameProperty); }
set { SetValue (EventNameProperty, value); }
}
public ICommand Command {
get { return (ICommand)GetValue (CommandProperty); }
set { SetValue (CommandProperty, value); }
}
public object CommandParameter {
get { return GetValue (CommandParameterProperty); }
set { SetValue (CommandParameterProperty, value); }
}
public IValueConverter Converter {
get { return (IValueConverter)GetValue (InputConverterProperty); }
set { SetValue (InputConverterProperty, value); }
}
protected override void OnAttachedTo (View bindable)
{
base.OnAttachedTo (bindable);
RegisterEvent (EventName);
}
protected override void OnDetachingFrom (View bindable)
{
DeregisterEvent (EventName);
base.OnDetachingFrom (bindable);
}
void RegisterEvent (string name)
{
if (string.IsNullOrWhiteSpace (name)) {
return;
}
EventInfo eventInfo = AssociatedObject.GetType ().GetRuntimeEvent (name);
if (eventInfo == null) {
throw new ArgumentException (string.Format ("EventToCommandBehavior: Can't register the '{0}' event.", EventName));
}
MethodInfo methodInfo = typeof(EventToCommandBehavior).GetTypeInfo ().GetDeclaredMethod ("OnEvent");
eventHandler = methodInfo.CreateDelegate (eventInfo.EventHandlerType, this);
eventInfo.AddEventHandler (AssociatedObject, eventHandler);
}
void DeregisterEvent (string name)
{
if (string.IsNullOrWhiteSpace (name)) {
return;
}
if (eventHandler == null) {
return;
}
EventInfo eventInfo = AssociatedObject.GetType ().GetRuntimeEvent (name);
if (eventInfo == null) {
throw new ArgumentException (string.Format ("EventToCommandBehavior: Can't de-register the '{0}' event.", EventName));
}
eventInfo.RemoveEventHandler (AssociatedObject, eventHandler);
eventHandler = null;
}
void OnEvent (object sender, object eventArgs)
{
if (Command == null) {
return;
}
object resolvedParameter;
if (CommandParameter != null) {
resolvedParameter = CommandParameter;
} else if (Converter != null) {
resolvedParameter = Converter.Convert (eventArgs, typeof(object), null, null);
} else {
resolvedParameter = eventArgs;
}		
if (Command.CanExecute (resolvedParameter)) {
Command.Execute (resolvedParameter);
}
}
static void OnEventNameChanged (BindableObject bindable, object oldValue, object newValue)
{
var behavior = (EventToCommandBehavior)bindable;
if (behavior.AssociatedObject == null) {
return;
}
string oldEventName = (string)oldValue;
string newEventName = (string)newValue;
behavior.DeregisterEvent (oldEventName);
behavior.RegisterEvent (newEventName);
}
}

Also for this to work you will need the BehaviorBase class which can be found below:

public class BehaviorBase<T> : Behavior<T> where T : BindableObject
{
public T AssociatedObject { get; private set; }
protected override void OnAttachedTo (T bindable)
{
base.OnAttachedTo (bindable);
AssociatedObject = bindable;
if (bindable.BindingContext != null) {
BindingContext = bindable.BindingContext;
}
bindable.BindingContextChanged += OnBindingContextChanged;
}
protected override void OnDetachingFrom (T bindable)
{
base.OnDetachingFrom (bindable);
bindable.BindingContextChanged -= OnBindingContextChanged;
AssociatedObject = null;
}
void OnBindingContextChanged (object sender, EventArgs e)
{
OnBindingContextChanged ();
}
protected override void OnBindingContextChanged ()
{
base.OnBindingContextChanged ();
BindingContext = AssociatedObject.BindingContext;
}
}

Usage:

   <ListView.Behaviors>
<local:EventToCommandBehavior EventName="ItemSelected" Command="{Binding SelectedClient}" />
</ListView.Behaviors>

Goodluck feel free to get back if you have questions

If you are trying to keep the selected item of ListView in your ViewModel, then use the SelectedItem property in the ListView like below,

 <ListView x:Name="ClientListView"
SelectedItem="{Binding SelectedClient}">