Wpf change the Visiblity of button if the checkbox is not checked

This is my recourse converter

 <BooleanToVisibilityConverter x:Key="BoolToVisConverter" />

And I have 2 buttons and 1 checkobox

the add button I want to show if the checkbox is checked and the edit button I want to show if the checkbox is not checked

<Button x:Name="Update"  Content="שמור שינויים" Grid.Row="3"  Height="30" Visibility="{Binding IsChecked  ,TargetNullValue=true, ElementName=Checked, FallbackValue=Hidden, Converter={StaticResource BoolToVisConverter}}" Margin="10,23,10,22" Background="LightBlue"  FontSize="15" Click="upDate_Click"  />
        <Button x:Name="Add"  Content=" הוספה" Grid.Row="4"  Height="30" Visibility="{Binding !IsChecked , FallbackValue=Visible, TargetNullValue=false, ElementName=Checked, Converter={StaticResource BoolToVisConverter}}" Margin="10,10,10,35" Background="LightBlue"  FontSize="15" Click="Add_Click"  />
        <CheckBox x:Name="Checked" IsChecked="True"   />

but {Binding !IsChecked Not work

How can I hide element if checked?

Solution

Try use this converter:

public class InvertedBooleanToVisibilityConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is bool boolValue) {
                return !boolValue ? Visibility.Visible : Visibility.Collapsed;
            }
            return Visibility.Collapsed;
        }
    
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

and in your xaml.cs:

<Button x:Name="Add" Content=" הוספה" Grid.Row="4" Height="30"
            Visibility="{Binding IsChecked, ElementName=Checked, Converter={StaticResource InvertedBoolToVisConverter}}"
            Margin="10,10,10,35" Background="LightBlue" FontSize="15" />

do not forget to include the converter in the resources:

    <Window.Resources>
        <BooleanToVisibilityConverter x:Key="BoolToVisConverter" />
        <local:InvertedBooleanToVisibilityConverter x:Key="InvertedBoolToVisConverter" />
</Window.Resources>