UWP ObservableCollection<string> does not bind to TextBox - mvvm

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}"/>