Introduction
Model-View-ViewModel [MVVM] is a design pattern for developing the UI Applications. It is a variation of MVC and MVP. MVP[Model-View-Presenter] which has been using for years to develop UI platforms.
Bit about MVP
View is what you see on the screen.Model displays the data and Presenter hooks the two elements together.You can read more about this pattern . Continue reading...

The factory method pattern is a creational design pattern used in software development to encapsulate the process of creating the objects.
Concerns:

Which object needs to be created.
Managing the life time of the object.
Managing the build-up and tear down concerns of the object.

Definition:
“Define an interface for creating an object, but let subclasses decide which class to instantiate”

 
C# . Continue reading...