In order to implement persistence for our application's data, we need to do three things: save data, load data, and delete data. In this section, we're going to go through our ViewController class and remove all of the references to our old data model, and instead begin using our new Core Data compatible data model. As we go, we'll be introducing new ways of saving and loading our snippet data, and adding the ability to delete snippets.
With our old data model, saving data consisted of two steps: create a new instance of a SnippetData subclass, and then add it to our data array. Now, with Core Data, the process is pretty similar but it takes a few more lines of code and uses some new concepts.
Before we can get started with our new save mechanisms, we're going to make two small changes. First, add an import CoreData command at the top of the ViewController.swift file, with the other import statements. Then, change the type of our data array so that instead of [SnippetData...