RadioGroup SelectValue Binding - xaml

Question

Good morning
I have a problem with binding initial state for each radio button.
<StackLayout Orientation="Horizontal"
RadioButtonGroup.GroupName="{Binding Source}"
RadioButtonGroup.SelectedValue="{Binding Frequency}">
<RadioButton FontSize="10" Content="Never" Value="0"/>
<RadioButton FontSize="10" Content="Rare" Value="25"/>
<RadioButton FontSize="10" Content="Often" Value="75"/>
<RadioButton FontSize="10" Content="Always" Value="100"/>
</StackLayout>
When the view is loaded there is no any RadioButton selected. The source binding Frequency is of type double.
public double Frequency
{
get => GetPropertyValue<double>();
set => SetPropertyValue(value);
}
I was thinking it is related with comparassion of types object and double. I have created converter as below:
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (!int.TryParse(value.ToString(), out var intValue))
return value;
var result = FrequencyValues.GetValue(intValue).ToString();
return result;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
if (!int.TryParse(value.ToString(), out var intValue))
return value;
var result = FrequencyValues.GetValue(intValue);
return result;
}
The solution with converter is also not working. Is that related with comprassion of types or I am missing some knowledge?
Thanks!

Answer 1

try
<StackLayout
RadioButtonGroup.GroupName="Source"
RadioButtonGroup.SelectedValue="{Binding Frequency}"
>
<RadioButton Content="a" Value="1"
IsChecked="{Binding Frequency, Converter={StaticResource RadioIsCheckedConverter}, ConverterParameter={x:Reference page}}" />
<RadioButton Content="b" Value="2"
IsChecked="{Binding Frequency, Converter={StaticResource RadioIsCheckedConverter}, ConverterParameter={x:Reference page}}" />
</StackLayout>
converter
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value != null)
{
var radioButton = parameter as RadioButton;
if (radioButton != null && radioButton.Value.Equals(value))
{
return true;
}
}
return false;
}

Answer 2

Change the type of Frequency from Double to Object;
The same Xaml as yours.
Code behind:
public partial class Page1 : ContentPage
{
RadioButtonModel _viewModel;
public Page1()
{
InitializeComponent();
_viewModel = new RadioButtonModel() { Source = "Group1", Frequency="100" };
this.BindingContext = _viewModel;
}
}
public class RadioButtonModel : INotifyPropertyChanged
{
private object _frequency;
public object Frequency
{
get => _frequency;
set
{
_frequency = value;
GetPropertyValue(nameof(Frequency));
}
}
private string _source;
public string Source
{
get => _source;
set
{
_source = value;
GetPropertyValue(nameof(Source));
}
}
public event PropertyChangedEventHandler PropertyChanged;
void GetPropertyValue(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}