The design patterns of MVC (Model-View-Controller) and MVVM (Model-View-ViewModel) are both used in iOS development for managing the interaction between a user interface, business logic, and data. The main difference is that MVC separates the UI logic from the business logic by using a controller to manage the flow between the view and model, whereas MVVM uses a view model as an intermediary to separate the UI logic from the business logic. Both patterns aim to improve code readability, testability, and maintainability. By migrating from MVC to MVVM, developers can achieve more decoupling of concerns, making it easier to debug, test, and read code. The process involves identifying UI logic and business logic in existing code, creating a view model to handle the business logic, and then updating the controller to interact with the view model instead of directly accessing the model. This approach allows for more flexibility, reusability, and maintainability in iOS development.