Computed properties are useful in so many ways and within the context of SwiftUI they are even more powerful. We can use them to split up our view body while keeping access to the same data. Or we can derive new values from our state that will recalculate with every change. We can also use computed properties in model objects, observing and even setting their values via synthesized bindings.

Bindings are used to pass parts of our state down to a subview that might later on make changes to said state. We typically rely on the @State and @Binding property wrappers to generate bindings for us but bindings can also be constructed programmatically. In fact there’s a handful of cases in which creating bindings in an on-demand manner may just be the preferred option.

Complying to the Codable protocol is simple thanks to synthesized initializers and coding keys. Similarly making your class observable using the Combine framework is trivial with ObservableObject. But attempting to merge these two protocols in a single implementation poses a few obstables. Let’s find out!

In WWDC 2019 session Combine in Practice we learned how to apply the Combine Framework to perform validation on a basic sign up form built with UIKit. Now we want to apply the same solution to the SwiftUI version of that form which requires some adaptation.