How does One-Time binding differ from Two-Way binding in MvvmCross

One-Time Binding

One-Time binding is used to transfer data from the ViewModel to the View only once, when the binding source is set. After this initial transfer, the binding does not monitor changes to the ViewModel's properties and does not update the View unless the binding source itself is reset. This mode is useful for fields that are configurable but do not change frequently after being set. For example, in MvvmCross, One-Time binding is used for setting static text from language files, as the user typically selects a language once and rarely changes it afterward[1][10].

Two-Way Binding

Two-Way binding, on the other hand, establishes a continuous, bidirectional connection between the View and the ViewModel. Changes in either the View or the ViewModel trigger updates in the other. This mode is particularly useful when editing existing data, such as filling out forms, where both the user's input and any changes from the ViewModel need to be reflected in real-time. Two-Way binding is commonly used in MvvmCross and often serves as the default mode for new bindings[1][2].

Key Differences

- Direction of Data Flow: One-Time binding only updates the View from the ViewModel once, while Two-Way binding updates both the View and the ViewModel continuously.
- Change Monitoring: One-Time binding does not monitor changes after the initial update, whereas Two-Way binding continuously monitors and updates both ends.
- Use Cases: One-Time is ideal for static or infrequently changing data, whereas Two-Way is better suited for interactive forms or dynamic data exchange.

In summary, One-Time binding is used for static or initial data setup, while Two-Way binding is used for interactive scenarios where both the View and ViewModel need to reflect each other's changes in real-time.