Windows Phone 8.1 StringFormatConverter

StringFormatConverter.cs

public sealed class StringFormatConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        if (value == null)
            return null;

        if (parameter == null)
            return value;

        return string.Format((string)parameter, value);
    }

    public object ConvertBack(object value, Type targetType, object parameter,
        string language)
    {
        throw new NotImplementedException();
    }
}

XAML Fragments.xaml

<StringFormatConverter x:Name="StringFormat"/>	

<TextBlock Text="{Binding DateTime, StringFormat=T,	RelativeSource={RelativeSource TemplatedParent}}" />