In Swift, classes and structures are very similar. If we really want to master Swift, it is very important to understand what makes classes and structures so similar and also what sets them apart, because they are the building blocks of your applications. Apple describes classes and structures as:
Classes and structures are general-purpose, flexible constructs that become the building blocks of your program's code. You define properties and methods to add functionality to your classes and structures by using the already familiar syntax of constants, variables, and functions.
Let's begin by taking a quick look at some of the similarities between classes and structures.