Design patterns are solutions to software design problems that we tend to see over and over again in real-world application design. These patterns are designed to help us create reusable and flexible code. Design patterns can also make our code easier to read and understand for other developers and also for ourselves when we look back at our code months/years later.

If we look at the examples in this chapter carefully, we will notice that one of the backbones of design patterns is the protocol. Almost all design patterns (except the singleton design pattern) use protocols to help us create very flexible and reusable code.

If this was the first time that you have really looked at design patterns, you probably noticed some similarities to strategies that you have used in the past in your own code. This is expected when experienced developers are first introduced to design...