Check all checkboxes with a button, when the checkbox is placed inside itemscontrol and with databinding to an observable collection

See more:

WPF

checkbox

MVVM

data-binding

Hello,

I have a list of string and checkboexes. It has two properties one is the ItemName and one is the CheckedStatus. I want this button to be able to check all the checkboxes.

<ItemsControl Name="IC" ItemsSource="{Binding ItemsSorted}">
 <ItemsControl.ItemTemplate>
  <DataTemplate>
    <StackPanel>
      <CheckBox Name="Mycb" IsThreeState="False"
        FontSize="12" Foreground="WhiteSmoke" 
        Content="{Binding ItemName}" IsChecked="{Binding IsChecked}"/>
    </StackPanel>
   </DataTemplate>
  </ItemsControl.ItemTemplate>
 </ItemsControl>

Then I have here the button in the same Window but outside the ItemsControl of course

<Button Grid.Row="1" Content="Select All" Name="SelectAll" Style="{StaticResource ButtonStyle}" MinWidth="150" Margin="0,5,20,20" Click="SelectAll_Click"/>

Here is the WindowAViewModel.cs

public WindowAViewModel(string pageTitle, WindowBViewModel windowBViewModel)
        {
            PageTitle = pageTitle;

            MyItems.Add(new MyCustomItemViewModel("Apple", windowBViewModel));
            MyItems.Add(new MyCustomItemViewModel("Orange", windowBViewModel));
            MyItems.Add(new MyCustomItemViewModel("Banana", windowBViewModel));
        }

Here is MyCustomItemViewModel.cs

[ImplementPropertyChanged]
    public class MyCustomItemViewModel
    {
        public string ItemName { get; set; }
        public bool IsChecked { get; set; }
        public WindowBViewModel WindowBViewModelObj { get; set; }

        public MyCustomItemViewModel(string itemName, WindowBViewModel windowBViewModel)
        {
            ItemName = itemName;
            WindowBViewModelObj = windowBViewModel;
        }

        private void OnIsCheckedChanged()
        {
            if (IsChecked)
                WindowBViewModelObj.MyItems.Add(this);
            else
                WindowBViewModelObj.MyItems.Remove(this);
        }
    }

and here is the BaseWindowViewModel.cs

public class BaseWindowViewModel
    {
        public string PageTitle { get; set; }

        private ObservableCollection<MyCustomItemViewModel> _myItems;
        public ObservableCollection<MyCustomItemViewModel> MyItems
        {
            get
            {
                if (_myItems == null)
                {
                    _myItems = new ObservableCollection<MyCustomItemViewModel>();
                    _myItemsSorted = CollectionViewSource.GetDefaultView(_myItems);
                    _myItemsSorted.SortDescriptions.Add(new SortDescription() { PropertyName = "ItemName" });
                }
                return _myItems;
            }
        }

        private ICollectionView _myItemsSorted;
        public ICollectionView MyItemsSorted { get { return _myItemsSorted; } }
    }

What I have tried:

I have tried this:

private void SelectAll_Click(object sender, RoutedEventArgs e)
  {
  foreach (var currentItem in IC.Items)
     {
     var container = IC.ItemContainerGenerator.ContainerFromItem(currentItem) as FrameworkElement;
     var checkBox = container.FindName("Mycb") as CheckBox;
         {
            checkBox.IsChecked = true;
         }
        }
       }

but threw an exception "System.NullReferenceException: 'Object reference not set to an instance of an object.'"