Lecture 13 of Stanford’s iOS Development course from Spring 2021 covers the basics of the Publisher protocol. We’ll use it to implement a much cleaner, more readable version of our background downloading code. After that, two other important persistence mechanisms, CloudKit and CoreData, are introduced and briefly explained. CloudKit is a mechanism for storing the user’s data in the cloud so that it will appear on all of their devices. The relevant data types are discussed as well as the basics of its API for creating records, querying them, and interacting with them in your code. CoreData is a framework for an object-oriented database layered on top of a relational database. CoreData was demonstrated in the Spring 2020 iteration of CS193p.