I'm stuck on the first section of the Bookworm project.

I've updated the built-in data model, Persistence.swift, and BookwormApp.swift.

But every time I try to add a new book, the app crashes and I get the following error:

Thread 1: Fatal error: UnsafeRawBufferPointer with negative count

It seems the error is occuring in BookwormApp.swift where the @main property wrapper is.

However, any time I delete it, I get this error:

entry point (_main) undefined. for architecture x86_64

Here's what I have in BookwormApp.swift

import SwiftUI
@main
struct BookwormApp: App {
    let persistenceContainer = PersistenceController.shared

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(\.managedObjectContext, persistenceContainer.container.viewContext)
        }
    }
}

And what I have in Persistence.swift

import CoreData

struct PersistenceController {
    static let shared = PersistenceController()

    let container: NSPersistentContainer

    init() {
        container = NSPersistentContainer(name: "bookworm")

        container.loadPersistentStores{ (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolve Error: \(error)")
            }
        }
    }
}

And here's my project on Github.

What am I doing wrong?

Thanks in advance for your help!

Hi Natasha

The @main is the entry point for the app so you have to have that there. Some time error occurs next to it but does not usually mean that is the problom is there it just that where the compiler has entered. I looked at your code and @Fly0strich is correct that if you change "bookworm" to "Bookworm" because .xcdatamodelid is name Bookworm and it looking for that file and can not find it which is why you are getting the Fatel error.