This course provides a comprehensive overview of Design Patterns in C# and .NET from a practical perspective. This course in particular covers patterns with the use of:
The latest versions of C# and the .NET framework
Use of modern programming approaches: dependency injection, reactive programming and more
Use of modern developer tools such as ReSharper
Discussions of pattern variations and alternative approaches
This course provides an overview of all the Gang of Four (GoF) design patterns as outlined in their seminal book, together with modern-day variations, adjustments, discussions of intrinsic use of patterns in the language.
What are Design Patterns?
Design Patterns are reusable solutions to common programming problems. They were popularized with the 1994 book Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, John Vlissides, Ralph Johnson and Richard Helm (who are commonly known as a Gang of Four, hence the GoF acronym).
The original book was written using C++ and Smalltalk as examples, but since then, design patterns have been adapted to every programming language imaginable: C#, Java, PHP and even programming languages that aren't strictly object-oriented, such as javascript.
The appeal of design patterns is immortal: we see them in libraries, some of them are intrinsic in programming languages, and you probably use them on a daily basis even if you don't realize they are there.

https://www.udemy.com/course/design-patterns-csharp-dotnet/