How to implement bidirectional data binding in iOS using MVVM?

In iOS, there are several ways to achieve MVVM bidirectional data binding:

1. Key-Value Observing (KVO): Utilizing KVO to observe changes in the properties of model objects and updating views in the observer. When a user makes changes to a view, the new value can be synchronized to the model object through KVO.
2. Reactive programming frameworks (such as ReactiveCocoa, RxSwift) provide a way to implement data binding using signals or observable sequences. When the properties of model objects change, signals or observable sequences are sent, allowing views to subscribe to these signals to receive data. Views then use these signals to synchronize new values back to the model objects when the user interacts with them.
3. Implementing manually: In the view controller, observing changes in the view, and upon detecting changes, manually updating the properties of the model object and updating the view in the setter method of the model object.

Regardless of the method used, it is necessary to establish a binding relationship between the view and the model, and achieve bidirectional data transfer. This allows for updating the view when the model changes, and updating the model when the view changes, thus achieving bidirectional data binding in MVVM.