With just a little bit of work we have modeled a new domain type for our application, created a relationship between domain types, and created a new view to display the data for this new type, as well as navigation to the view. And this sets the stage for how one can build a simple SQLite-based application. In the onAppear of a feature’s view you can execute some queries to populate the data in the view, and then SwiftUI takes care of the rest.

But also most apps cannot be so simple. Typically you will have lots of features accessing the database, and then also lots of features writing to the database. And when one features makes a write you will want to make sure that all other views update in order to show the freshest data.

This brings us to a powerful feature that SQLite has called “change notifications”. We didn’t explore this when dealing with the C library directly because it can be quite cumbersome due to how one handles callback functions in C. But luckily GRDB has a nice interface to this functionality, so let’s take a look.