Explain MVVM-C architecture and why it is used in large iOS apps

MVVM-C adds a Coordinator layer to MVVM to manage navigation separately.

MVVM-C introduces Coordinators to handle navigation logic outside ViewControllers. ViewModels handle business logic, Views handle UI rendering, and Coordinators manage flow. This reduces ViewController complexity and improves reusability and testability. It is especially useful in apps with deep navigation hierarchies.