CloudKit is a service that Apple created as a simple tool for application developers to store data on a remote server. The beauty of this service is that any user with an iCloud account can be identified automatically by CloudKit, meaning you can begin connecting data to your user immediately without having them first sign up for your service.

Signup screens are often considered to be dealbreakers for users because they don't want to share their email address with certain apps, or just because they think signing up for a particular app isn't worth the effort. With CloudKit, you can remove all this friction because users are discretely logged into your app using the iCloud account that they already use on their device.

When you add CloudKit to your app, you will find that it offers a lot of great functionalities to help you keep the number of web requests as low as possible, and you can even have CloudKit notify your app when something changes on the remote server even when your app isn't running. Apple uses features such as these extensively in their own applications to try to make sure that their apps provide a seamless experience between devices.

To add CloudKit to the MustC app, you don't need to do a lot of work. All you need to do is make sure your project is set up correctly and enable the required capabilities for your app.