CoreData simple crud

gistfile1.txt

lazy var persistentContainer: NSPersistentContainer = {
        /*
         The persistent container for the application. This implementation
         creates and returns a container, having loaded the store for the
         application to it. This property is optional since there are legitimate
         error conditions that could cause the creation of the store to fail.
        */
        
        let container = NSPersistentContainer(name: "CoreDataExample")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                 
                /*
                 Typical reasons for an error here include:
                 * The parent directory does not exist, cannot be created, or disallows writing.
                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
                 * The device is out of space.
                 * The store could not be migrated to the current model version.
                 Check the error message to determine what the actual problem was.
                 */
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        return container
    }()

    // MARK: - Core Data Saving support

    func saveContext () {
        let context = persistentContainer.viewContext
        if context.hasChanges {
            do {
                try context.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nserror = error as NSError
                fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
            }
        }
    }
    

class ViewController: UIViewController {
    static func instantiate() -> ViewController {
        let storyBoard = UIStoryboard(name: "Main", bundle: .main)
        let vc = storyBoard.instantiateViewController(withIdentifier: String(describing: Self.self)) as! ViewController
        return vc
    }
    
    var listRefreshTrigger: (() -> ())?
    
    @IBOutlet weak var titleTF: UITextField!
    @IBOutlet weak var descriptionTV: UITextView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        
    }
    
    @IBAction func saveTapped() {
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        let todo = ToDo(context: context)
        todo.id = .init()
        todo.taskName = titleTF.text
        todo.taskDescription = titleTF.description
        
        (UIApplication.shared.delegate as! AppDelegate).saveContext()
        
        listRefreshTrigger?()
        self.dismiss(animated: true)
    }

}


class TableViewController: UITableViewController {
    
    var data: [ToDo]? {
        didSet {
            tableView.reloadData()
        }
    }
    
    @IBAction func addButtonTapped(_ sender: UIBarButtonItem) {
        let vc = ViewController.instantiate()
        vc.listRefreshTrigger = { [weak self] in
            self?.refreshFromDatabase()
        }
        self.present(vc, animated: true)
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        
        refreshFromDatabase()
    }
    
    func refreshFromDatabase() {
        let fetchRequest = ToDo.fetchRequest()
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        
        let objects = try? context.fetch(fetchRequest)
        self.data = objects
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.data?.count ?? 0
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        
        let cell = UITableViewCell(style: .subtitle, reuseIdentifier: "cell")
        cell.textLabel?.text = data?[indexPath.row].taskName
        cell.detailTextLabel?.text = data?[indexPath.row].taskDescription
        return cell
    }
}