Explain the concept of StreamController and its use cases in Flutter.

StreamController in Dart is a powerful class for managing streams. It can be used to create custom stream controllers that control the flow of data in Dart applications. In Flutter, StreamControllers are often employed to handle user interface events, manage state, and facilitate communication between different parts of a Flutter app. Understanding the use cases and principles behind StreamController is crucial for effective state management and event handling in Flutter applications.