gistfile1.txt

final class PersistentStack {

    private let storeUrl: URL
    private let modelUrl: URL

    private lazy var managedObjectModel: NSManagedObjectModel = {
        guard let model = NSManagedObjectModel(contentsOf: modelUrl) else {
            fatalError("Cannot find model file with URL: \(modelUrl)")
        }
        return model
    }()

    private lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
        let persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: managedObjectModel)
        do {
            try persistentStoreCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeUrl, options: nil)
        } catch {
            fatalError("Cannot add persistent store with URL: \(storeUrl)")
        }
        return persistentStoreCoordinator
    }()

    lazy var managedObjectContext: NSManagedObjectContext = {
        let managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = persistentStoreCoordinator
        managedObjectContext.undoManager = UndoManager()
        return managedObjectContext
    }()

    init(with storeUrl: URL, and modelUrl: URL) {
        self.storeUrl = storeUrl
        self.modelUrl = modelUrl
    }

}