UWP ObservableCollection<string> does not bind to TextBox

Question

In XAML, I have an ItemsControl binded to an ObservableCollection<string>.
Inside it as ItemControl.ItemTemplate, a TextBox binded to the string.

<ItemsControl ItemsSource="{x:Bind ViewModel.MyNames, Mode=TwoWay}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
                <TextBox Text="{Binding Mode=TwoWay}"/>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

public ObservableCollection<string> MyNames = new ObservableCollection<string> {"aa", "bb", "cc" };

If I edit any text box I receive the Error:

Error      
Cannot save value from target back to source. Binding: Path='' DataItem='Windows.Foundation.IReference`1<String>';
target element is 'Windows.UI.Xaml.Controls.TextBox' (Name='null');
target property is 'Text' (type 'String')      

How do I link the text box to the string value? While respecting MVVM pattern of course. x:Bind I don't know if it can bind to the default value given by ItemsSource.

Answer 1

A string is immutable and cannot be modified.

If you want to just display the values from the ObservableCollection<string> in the TextBoxes, you could use a OneWay binding:

<TextBox Text="{Binding Mode=OneWay}"/>

If you want to be able to edit the values, you need to replace the ObservableCollection<string> with an ObservableCollection<YourType> where YourType is a custom type which has a string property that can be set to a new value:

public class ViewModel
{
    public ObservableCollection<CustomType> MyNames = 
        new ObservableCollection<CustomType> 
        { 
            new CustomType { Value ="aa" },
            new CustomType { Value ="bb" },
            new CustomType { Value ="cc" }
        };
}

public class CustomType
{
    public string Value { get; set; }
}

XAML:

<TextBox Text="{Binding Value}"/>