Flutter The Observer pattern allows you to define entities that send events and another entity that subscribes to those events. Let's see how to use them in Flutter; we'll look at the concept, usage examples, and recommendations.

Flutter Simply put, a singleton ensures that a class has only one instance in all applications and provides a global access point. We will see how to use it in Flutter.

Android The Template Method pattern allows you to define the general structure of an algorithm in a superclass and delegate specific details to subclasses. It is useful to avoid code duplication and provide a flexible structure for algorithm implementation.