Understanding Bindings in MvvmCross: Source and Target Concepts

In MvvmCross, when creating bindings, it's important to understand the distinction between Source and Target[1].

* Target: The Target is the property on your View that you are binding[1]. It refers to any public property on a View that you want to bind, such as `Text`, `ItemsSource`, or `SelectedItem`[1]. In MvvmCross, any public property on a View can be bound in `OneWay` mode[1].
* Source: The Source is the property in your ViewModel that your View binds to[1]. The Source in your ViewModel also needs to be a public property[1]. If you implement `INotifyPropertyChanged` on your ViewModel and raise the `NotifyPropertyChanged` event when updating your properties, the MvvmCross binding engine will know how to feed the value to the Target[1][5].

MvvmCross uses `TargetBinding` to define how a View can bind when modes other than `OneWay` are desired[1]. If you want to bind something in `TwoWay` mode, a `TargetBinding` must exist to describe how to achieve this[1]. Internally, a `TargetBinding` typically subscribes to `EventHandler`s to relevant events in order to notify when something has changed on the View, so that the changes can be fed back to the ViewModel[1]. You can create your own `TargetBinding`[1][4].

Binding Expressions

* Swiss/Tibet: Android bindings and some string binding descriptions use Swiss/Tibet binding expressions, a description language specific to MvvmCross[1].

In this case, `SomeView` is the bindable object (the View), `ViewProperty` is the Target, and `ViewModelProperty` is the Source[1].
* XAML: In XAML binding expressions, bindings typically look like this:

`SomeView` is the bindable object, `ViewProperty` is the Target, and `ViewModelProperty` is the Source[1]. With MvvmCross XAML BindingEx extensions, which use Swiss/Tibet, you can alternatively bind like this:

* Fluent Bindings: MvvmCross also offers Fluent Bindings to create type-safe binding expressions in code behind[1]. For these to work, the place where you create the fluent binding must inherit from `IMvxBindingContextOwner`, meaning the type will have a `BindingContext` property that the Fluent Binding will use to find the Source[1][3]. These Fluent Bindings usually look like this:


    var set = this.CreateBindingSet();
    set.Bind(someView)
    .For(view => view.ViewProperty)
    .To(viewModel => viewModel.ViewModelProperty);

The `ContextOwnerType` is usually a `MvxViewController`, `MvxTableViewCell`, or `MvxActivity`. This is typically the type containing the views you want to bind to[1]. When using the `BindingSet.Bind()` method, it expects the Target as an argument, typically the actual View you want to bind to[1].

Citations:
[1] https://blog.ostebaronen.dk/2018/01/mvvmcross-binding-target.html
[2] https://stackoverflow.com/questions/30146384/how-to-bind-mvxtableviewsource-to-dynamically-created-viewmodel-with-mvvmcross-a/30229955
[3] https://stackoverflow.com/questions/30146384/how-to-bind-mvxtableviewsource-to-dynamically-created-viewmodel-with-mvvmcross-a
[4] https://www.mvvmcross.com/documentation/advanced/custom-data-binding
[5] https://www.packtpub.com/en-us/learning/how-to-tutorials/sharing-mvvmcross
[6] https://canbilgin.wordpress.com/tag/mvvmcross/
[7] https://www.mvvmcross.com/documentation/fundamentals/value-converters
[8] https://github.com/MvvmCross/MvvmCross/issues/87

Can you explain the difference between Source and Target in MvvmCross bindings