When we build things in Swift that interact with other types, we often specify the type we are interacting with directly. This is helpful because it means we know the capabilities that the type has; we can put those capabilities to use and ensure that the outputs have the correct type. However, we now have a construct that can only interact with the specified type; it can't be reused with other types, even if the concepts are the same.

Generics give us the advantage of having a defined type while being generically applicable to other types. It is, perhaps, best illustrated with an example.

In this recipe, we will create a generic class that stores the last five things it was given and returns them all upon request.

Getting ready

We will create a custom collection object that will store the last five strings that the user copied so that they can paste not just the last string copied, but any of the last five. You can add strings to the list and ask for all...