SwiftUI Navigation: Decoupling

So, this is absolutely incredible. By making use of the powerful domain modeling tools that Swift gives us, such as enums, and by integrating all of our features together, we have an application that can deep link into any state in an instant, and we can write powerful, nuanced tests for features in isolation or the integration of multiple features.

So, we just wanted to take the time to show how our SwiftUINavigation library can allow you to write a modern, vanilla SwiftUI application with precise domain modeling.

Just really, really cool stuff.

So, what’s the problem then? Why did Apple go and completely revamp the way navigation links work in SwiftUI?

Well, there were a few problems. Some things were very in-your-face and obvious, such as numerous bugs, especially when it came to deep linking multiple levels. Other things were not as obvious at first blush, but became apparent as applications grow bigger and more complex, such as a tight coupling of the source of navigation with the destination being navigated to.

Let’s take a look at both of these problems so that we can understand why they are so pernicious, and then that will help us understand why the navigation link APIs were changed the way they were.

Let’s start with the bugs. There are plenty of navigation bugs, but the one that would get everyone sooner or later is that you cannot deep link in a navigation view more than 2 layers. We haven’t run into that problem in our inventory app because so far the maximum number of levels you can drill down is two: first to the item screen, and then to the color picker.

It may seem lucky that we didn’t have to drill down 3 levels in the app, but honestly we consciously engineered the app specifically to avoid that problem. So, we can’t see the problem in the app currently, but let’s quickly stub a view into the application that clearly shows something going wrong.