Adding the @Observable macro

The primary goal of the Observation framework is to simplify our work as much as possible, and it does that with the heavy use of macros.

Let’s take a Book class, for example:

class Book: ObservableObject {
    @Published var title:String = ""
    @Published var author: String = ""
    @Published var publishedYear: Date = Date()
    @Published var numberOfPages: Int = 0
}

The Book class is a standard ObservableObject class that contains four properties with a @Published property wrapper.

Using the Observation framework, we can get rid of all the property wrappers and the ObservableObject protocol and just add a macro attached to the class declaration:

@Observable
class Book {
    var title:String = ""
    var author: String = ""
    var publishedYear: Date...