MAUI IOS - Radio Button will not show selected on initial load of the page

I have a page in my app that shows data with radio buttons. As expected, one of them should show selected when the page loads, but no matter what I do, all the radio buttons show unselected. Here is my radio button definition. I should mention this is within a collectionview, one of 3 properties. As well, each button shows for each line, but none of them show selected.

 <RadioButton x:Name="RbSelect" Grid.Column="6" Grid.Row="0"
 CheckedChanged="RadioButton_CheckedChanged"
 GroupName="RadioGroup" IsChecked="{Binding RbSelected}">
 <RadioButton.Content>
     <StackLayout>
         <Label
             Margin="30,0,0,0"                                            
             TextColor="{StaticResource FieldNameTextColor}"
             VerticalOptions="Start" />
     </StackLayout>
 </RadioButton.Content>

Here is my code where I am trying to set the value. This is my latest attempt, however, I have tried a ton of different solutions.

    public UpdateCars(ObservableCollection<AutoWithSwitch> value, CollectionView updateCarsViewModel)
{           
    InitializeComponent();           
    updateCarsViewModel.ItemsSource = null;           
    
    foreach (var item in value)
    {
        if (item.IsChecked)
            RbSelect.IsChecked = true;
        else
            RbSelect.IsChecked = true;
    }
    updateCarsViewModel.ItemsSource = value;
}

Solution

As I understand it, you're trying to bind the RadioButton members of a data template in your CollectionView where ItemsSource is ObservableCollection<AutoWithSwitch>. When I tried to reproduce your issue as minimally as possible from your code, I was getting some complaints from iOS about not liking the fact that a StackLayout (the error just referred to it as a View) was being set as RadioButton.Content. That "may or may not" affect what you're seeing. I do understand what you're trying to do with the margin on the Label but this seemed to be a big problem when building it so I margined the label by wrapping both in a horizontal stack.

Other than that, the bindings seemed to work OK, however one difference is that I'm binding directly to an enum value and not using the GroupName property because that makes it redundant. You say you've tried "a ton of different solutions" and I hope that one more won't hurt and that it gives you something new to try.

MainPage xaml with Mock ListView of type: ObservableCollection<AutoWithSwitch>

This xaml forward-references a EnumToBooleanConverter that is defined below.

<ContentPage 
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"             
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"             
    xmlns:local ="clr-namespace:maui_radio_buttons"             
    x:Class="maui_radio_buttons.MainPage">
    <ContentPage.BindingContext>
        <local:MainPageBindingContext/>
    </ContentPage.BindingContext>
    <ContentPage.Resources>
        <ResourceDictionary>
            <local:EnumToBooleanConverter x:Key="EnumToBoolConverter" />
        </ResourceDictionary>
    </ContentPage.Resources>
    <CollectionView ItemsSource="{Binding AutoWithSwitchCollection}">
        <CollectionView.ItemTemplate>
            <DataTemplate>
                <Frame Padding="5" CornerRadius="10">
                    <Grid    
                        RowSpacing="2"
                        BackgroundColor="White" 
                        Padding="5"
                        RowDefinitions="Auto,Auto"
                        ColumnDefinitions="*,*,*">
                        <Label 
                            Grid.Column="0"
                            Grid.Row="0"
                            Grid.ColumnSpan="3"
                            HorizontalOptions="Fill"
                            HorizontalTextAlignment="Center"
                            Text="{Binding Description}" 
                            FontSize="Medium"/>
                        <HorizontalStackLayout
                                Grid.Column="0"
                                Grid.Row="1">
                            <RadioButton
                                GroupName="RadioGroup"
                                WidthRequest="50"
                                IsChecked="{Binding CarType, Converter={StaticResource EnumToBoolConverter}, ConverterParameter=Tesla}"/>
                            <Label
                                Text="Tesla"
                                Margin="10,0,0,0" 
                                VerticalTextAlignment="Center"
                                HorizontalTextAlignment="Center" />
                        </HorizontalStackLayout>
                        <HorizontalStackLayout
                                Grid.Column="1"
                                Grid.Row="1">
                            <RadioButton
                                GroupName="RadioGroup"
                                WidthRequest="50"
                                HeightRequest="30"
                                IsChecked="{Binding CarType, Converter={StaticResource EnumToBoolConverter}, ConverterParameter=Audi}"
                                HorizontalOptions="Fill"/>
                                <Label 
                                    Text="Audi"
                                    Margin="10,0,0,0" 
                                    VerticalTextAlignment="Center"
                                    HorizontalTextAlignment="Center" />
                        </HorizontalStackLayout>
                        <HorizontalStackLayout
                                Grid.Column="2"
                                Grid.Row="1">
                            <RadioButton
                                GroupName="RadioGroup"
                                WidthRequest="50"
                                IsChecked="{Binding CarType, Converter={StaticResource EnumToBoolConverter}, ConverterParameter=Porsche}"
                                HorizontalOptions="Fill"/>
                            <Label 
                                Text="Porsche"
                                Margin="10,0,0,0" 
                                VerticalTextAlignment="Center"
                                HorizontalTextAlignment="Center" />
                        </HorizontalStackLayout>
                    </Grid>
                </Frame>
            </DataTemplate>
        </CollectionView.ItemTemplate>
    </CollectionView>
</ContentPage>

Mock AutoWithSwitch

enum CarType
{
    Tesla,
    Audi,
    Porsche,
}
class AutoWithSwitch: INotifyPropertyChanged
{
    public string Description
    {
        get => _description;
        set
        {
            if (!Equals(_description, value))
            {
                _description = value;
                OnPropertyChanged();
            }
        }
    }
    string _description = string.Empty;

    public CarType CarType
    {
        get => _carType;
        set
        {
            if (!Equals(_carType, value))
            {
                _carType = value;
                OnPropertyChanged();
            }
        }
    }
    CarType _carType = CarType.Tesla;

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged([CallerMemberName] string propertyName = null) =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

MainPage C#

public partial class MainPage : ContentPage
{
    int count = 0; bool isButtonClicking = false;
    public MainPage()
    {
        InitializeComponent();
        BindingContext.AutoWithSwitchCollection.Add(new AutoWithSwitch
        {
            Description = "Tesla Model S",
            CarType = CarType.Tesla,
        });
        BindingContext.AutoWithSwitchCollection.Add(new AutoWithSwitch
        {
            CarType = CarType.Audi,
            Description = "Audi R8",
        });
        BindingContext.AutoWithSwitchCollection.Add(new AutoWithSwitch
        {
            CarType = CarType.Porsche,
            Description = "Porsche 911 Turbo",
        });
    }
    new MainPageBindingContext BindingContext => (MainPageBindingContext)base.BindingContext;
}
class MainPageBindingContext : INotifyPropertyChanged
{
    public ObservableCollection<AutoWithSwitch> AutoWithSwitchCollection { get; } = new ObservableCollection<AutoWithSwitch>();

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged([CallerMemberName] string propertyName = null) =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

IValueConverter EnumToBooleanConverter

public class EnumToBooleanConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value == null || parameter == null)
            return false;
        string enumValue = value.ToString();
        string targetValue = parameter.ToString();
        return enumValue.Equals(targetValue, StringComparison.InvariantCultureIgnoreCase);
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is bool && (bool)value)
        {
            return Enum.Parse(targetType, parameter.ToString(), true);
        }
        return Binding.DoNothing;
    }
}