Can you provide an example of using One-Time binding with a TextView in MvvmCross

Understanding One-Time Binding

One-Time binding in MvvmCross is a mode where the data is transferred from the ViewModel to the View only once. After the initial transfer, the binding does not monitor changes and does not perform any updates unless the binding source itself is reset[1].

Example Implementation

To use One-Time binding with a `TextView`, you would typically set up the binding in your layout file using the `MvxBind` attribute. However, as noted in the documentation, One-Time bindings are not commonly used because they do not update the View if the ViewModel changes after the initial binding[1].

Here's an example of how you might set up a One-Time binding for a `TextView` in your layout file:

xml

In this example, `MyStaticText` is a property in your ViewModel that you want to bind to the `Text` property of the `TextView`. The `Mode=OneTime` parameter specifies that this binding should only occur once.

Important Considerations

- Recycling Views: If you are using a `RecyclerView`, One-Time bindings may not work as expected because views are recycled and reused. Each time a view is recycled and reused, the binding will be reapplied, which defeats the purpose of One-Time binding[2].

- Custom Bindings: If you need more control over how the binding works, you might need to create a custom binding. This involves creating a target binding class that defines how to bind a specific property[3].

Custom Binding Example

If you need to create a custom One-Time binding, you would typically subclass `MvxConvertingTargetBinding` or `MvxPropertyInfoTargetBinding` to define how the binding should work. Here's a simplified example of how you might create a custom One-Time binding:

csharp
public class CustomTextViewBinding : MvxConvertingTargetBinding
{
    private readonly TextView _textView;

    public CustomTextViewBinding(TextView textView) : base(textView)
    {
        _textView = textView;
    }

    protected override void SetValueImpl(object target, object value)
    {
        _textView.Text = (string)value;
    }

    public override Type TargetType
    {
        get { return typeof(string); }
    }

    public override MvxBindingMode DefaultMode
    {
        get { return MvxBindingMode.OneTime; }
    }
}

You would then need to register this custom binding in your setup class.

Conclusion

One-Time binding in MvvmCross is useful for static data that does not change frequently. However, it may not be suitable for dynamic or frequently updated data, and it can behave unexpectedly in scenarios like `RecyclerView` where views are recycled. Always consider the specific requirements of your application when choosing a binding mode.