XAML Value Converter With A Simple Example

• Convert()
• ConvertBack()

See the updated class now.

public class StringToBoolConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        throw new NotImplementedException();
    }
    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        throw new NotImplementedException();
    }
}

Now, we have to write the definition of these two methods. But before that, we must understand what we are going to do in both methods.

Convert()Convert() method takes data from Control; in our case, it will take string data from the textbox. And, we'll write custom code to convert that string into Bool value. See the method definition.

public object Convert(object value, Type targetType, object parameter, string language)
{
    bool CheckBoxStatus = false;
    if (!string.IsNullOrEmpty(value.ToString()))
    {
        if (value.ToString().ToUpper() == "CHECKED")
        {
            CheckBoxStatus = true;
        }
        else
        {
            CheckBoxStatus = false;
        }
    }
    return CheckBoxStatus;
}

Building necessary UI

Now, we are going to place controls using the XAML code. Open MainPage.xaml from Solution Explorer.

You'll get a blank grid like this.

Place a textbox and a checkbox into the Grid. Use the following XAML code for this.

<StackPanel Orientation="Vertical" HorizontalAlignment="Center" VerticalAlignment="Center">
    <TextBox VerticalAlignment="Center" Width="150" PlaceholderText="Enter your text"></TextBox>
    <CheckBox HorizontalAlignment="Center"></CheckBox>
</StackPanel>

After adding up the UI, we are supposed to add local resources. In this project, the local resource is a converter class that we added recently to our project. Now, we are supposed to provide a reference for that class to the XAML Code. So, add the following resource before the opening of Grid Tag in MainPage.xaml, as shown in the below picture.

Here is the code.

<Page.Resources>
    <local:StringToBoolConverter x:Key="StringToBoolConverterKey"></local:StringToBoolConverter>
</Page.Resources>

Don't forget to build your project, otherwise you'll see an exception in designers like this.

Our project setup and resources are ready. The next step is to bind the IsChecked property of the Checkbox with the string of the textbox. We've already written code for that. Now, we just have to mention that the code is binding in the following way.

Here is the code for you to copy from.

<CheckBox HorizontalAlignment="Center"
          IsChecked="{Binding Path=Text,
                              ElementName=txtBox,
                              Converter={StaticResource StringToBoolConverterKey}}">
</CheckBox>

Now, run the project and type some words in the textbox.

In my case, it is working fine. If you have any problems, please notify me via the Comments section.