Depending on how and when you began learning about software development, the concept of unit testing may or may not be a part of your vocabulary. Often used in bigger projects with larger teams, unit testing can be seen as a waste of time for smaller developers who don't have the time or resources to spend on writing tests.
Regardless of your past experiences with unit tests, they're a great tool and an important part of Xcode's toolset, and it will be up to you to decide when to use them. Before we get into how they work in Xcode, let's first talk a bit about unit tests in general.
So, the idea of testing seems pretty clear, but what exactly is a unit? It's up for a bit of interpretation, but generally you should think of a unit as the smallest piece of code that performs a discernible function. For example, if I have a function that processes some data and outputs some result, that could be a unit that we could test. In other cases, an entire class...