In SwiftUI #Preview is crashing when using @Environment property wrapper (Observable Macro)

I am using the Observable macro and when I use @Environment property wrapper to instance my model the preview stop working. Sample code below

import SwiftUI
import Observation

@Observable class Library {
    // ...
}

Now in my main app I created an instance of Library and add that instance to the environment

@main
struct BookReaderApp: App {
    @State private var library = Library()


    var body: some Scene {
        WindowGroup {
            LibraryView()
                .environment(library)
        }
    }
}

Now if I want to retrieve the Library instance from any view using the @Environment property wrapper the preview stop working completely (Assume the BoolView actually exist)

struct LibraryView: View {
    @Environment(Library.self) private var library
    
    var body: some View {
        List(library.books) { book in
            BookView(book: book)
        }
    }
}

#Preview {
    LibraryView()
}

If I go back and don’t use the Observable macro and just use the ObservableObject with @StateObject, .environemntObject and @EnvironmentObject the #Preview work fine.

This Observable macro is "related" new.
Any idea why this is happening? Is there any workaround? I am working with Xcode Version 15.2. Thanks in advance for any kind of help!

>Solution :

I’ve found out why. When you use the new Observation framework you need to declare this struct along with its extension (usually calling it ClassNameKey) this way:

private struct LibraryKey: EnvironmentKey {
    static var defaultValue: Library = Library()
}

extension EnvironmentValues {
    var library: Library {
        get { self[LibraryKey.self] }
        set { self[LibraryKey.self] = newValue }
    }
}

Then in your App struct you inject it using the path to it like this:

@main
struct BookReaderApp: App {
    @State private var library = Library()


    var body: some Scene {
        WindowGroup {
            LibraryView()
                .environment(\.library, library) // <-- Do it this way, using the path
        }
    }
}

And in any view you want to use your dependency you call it the same way, using the path: @Environment(\.library) private var library.
As for the previews, the dependency need to be injected this way:

#Preview {
    ContentView()
        .environment(\.library, Library())
}

If you want to know more go here: Observation Framework
Tell me if that worked for you!