tutorial - Eliminar datos de Coredata Swift

query core data swift 4

Question

En mi tableViewController tengo lo siguiente. Y estoy tratando de obtener borrar un elemento para que funcione.

var myData: Array<AnyObject> = []
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cellID: NSString = "Cell"
var Cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell
var data: NSManagedObject = myData[indexPath.row] as NSManagedObject
Cell.textLabel?.text = data.valueForKeyPath("Name") as? String
return Cell
}

Entonces para intentar y eliminar, tengo.

override func tableView(tableView: (UITableView!), commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
if editingStyle == .Delete {
let cellID: NSString = "Cell"
var Cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell
var data: NSManagedObject = myData[indexPath.row] as NSManagedObject
data.delete(0)
// Delete the row from the data source
//tableView!.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
} else if editingStyle == .Insert {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}

Answer 1

Swift 3.0

A continuación se muestra el código para eliminar el elemento y volver a cargar los datos.

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
let noteEntity = "Note" //Entity Name
let managedContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let note = notes[indexPath.row]
if editingStyle == .delete {
managedContext.delete(note)
do {
try managedContext.save()
} catch let error as NSError {
print("Error While Deleting Note: /(error.userInfo)")
}
}
//Code to Fetch New Data From The DB and Reload Table.
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: noteEntity)
do {
notes = try managedContext.fetch(fetchRequest) as! [Note]
} catch let error as NSError {
print("Error While Fetching Data From DB: /(error.userInfo)")
}
noteTableView.reloadData()
}

Answer 2

Actualice mi problema de codificación con la ejecución de una eliminación de datos en swed y coredata. Este es el código con el que terminé y funcionó.

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
switch editingStyle {
case .Delete:
// remove the deleted item from the model
let appDel:AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate
let context:NSManagedObjectContext = appDel.managedObjectContext!
context.deleteObject(myData[indexPath.row] as NSManagedObject)
myData.removeAtIndex(indexPath.row)
context.save(nil)
//tableView.reloadData()
// remove the deleted item from the `UITableView`
self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
default:
return
}
}

EDITAR arriba para Swift 2.2 y Xcode 7.3.1

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
switch editingStyle {
case .Delete:
// remove the deleted item from the model
let appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let context:NSManagedObjectContext = appDel.managedObjectContext
context.deleteObject(myData[indexPath.row] )
myData.removeAtIndex(indexPath.row)
do {
try context.save()
} catch _ {
}
// remove the deleted item from the `UITableView`
self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
default:
return
}
}

También era necesario corregir estas dos líneas de código.

 var myData: Array<AnyObject> = []
let managedObjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedObjectContext

Answer 3

Ninguna de las respuestas anteriores me ayudó en el caso de que estoy usando Core Data con un FetchedResultsController para un tableView . Como tal, aquí está mi implementación para manejar eliminar a continuación. Mi ejemplo utiliza un ejemplo simple suponiendo que desea eliminar una imagen de deslizar hacia la izquierda en una tabla y seleccionar la opción de eliminación predeterminada.

Swift 3 Solution for FetchedResultsController Implementaitons

Primero agregue este método delegado para la vista de tabla para permitir la edición cuando deslice la fila.

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
print("editing style delete detected")
let context = DataController.sharedInstance().managedObjectContext
let picture = self.fetchedResultsController.object(at: indexPath) as Pictures
context.delete(picture)
//Actually remove picture from storage on the device.
let fileManager = FileManager.default
let imagefilepath = "/(AppDelegate.appDelegate.applicationDocumentsDirectory())//(picture.filepath!)"
do {
try fileManager.removeItem(atPath: imagefilepath)
}
catch let error as NSError {
print("Ooops! Something went wrong while trying to delete picture file: /(error)")
}
//Save the context change.
AppDelegate.appDelegate.saveContext()
tableView.reloadData()//update changes
}
}

Una vez que haya hecho esto, asegúrese de que fetchedResultsController tenga su delegado configurado en su controlador e implemente estos métodos.

 func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch(type){
case .insert:
break;
case .delete:
print("delete detected on FRC Delegate")
tableView.deleteRows(at: [indexPath!], with: .fade)
break;
case .update:
break;
case .move:
break;
}
}

El secreto aquí es obtener acceso al objeto a través del método fetchedResultsController.object

let picture = self.fetchedResultsController.object(at: indexPath) as Pictures

De esta manera puedes correr

context.delete(picture)

que es inteligente sobre la eliminación de NSManagedObjects.

Información adicional relacionada con mi implementación (Lea solo a continuación si necesita más detalles)

-------------------------------------------------- -------------------------

Imagen + CoreDataProperties.swift

import Foundation
import CoreData
extension Pictures {
@nonobjc public class func fetchRequest() -> NSFetchRequest<Pictures> {
return NSFetchRequest<Pictures>(entityName: "Pictures");
}
@NSManaged public var date: NSDate?
@NSManaged public var desc: String?
@NSManaged public var filepath: String?
@NSManaged public var type: String?
@NSManaged public var workorder: Workorders?
}

Imágenes + CoreDataClass.swift

import Foundation
import CoreData
public class Pictures: NSManagedObject {
}

El siguiente archivo es mi controlador de pila coreData.

DataController.swift

import UIKit
import CoreData
class DataController: NSObject {
var managedObjectContext: NSManagedObjectContext
static var dataController: DataController!
override init() {
// This resource is the same name as your xcdatamodeld contained in your project.
guard let modelURL = Bundle.main.url(forResource: "WorkOrders", withExtension: "momd") else {
fatalError("Error loading model from bundle")
}
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
guard let mom = NSManagedObjectModel(contentsOf: modelURL) else {
fatalError("Error initializing mom from: /(modelURL)")
}
let psc = NSPersistentStoreCoordinator(managedObjectModel: mom)
managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = psc
let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
let docURL = urls[urls.endIndex-1]
/* The directory the application uses to store the Core Data store file.
This code uses a file named "DataModel.sqlite" in the application''s documents directory.
*/
let storeURL = docURL.appendingPathComponent("WorkOrders.sqlite")
do {
let options = [NSSQLitePragmasOption: ["journal_mode": "DELETE"]]
try psc.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeURL, options: options)
} catch {
fatalError("Error migrating store: /(error)")
}
}
class func sharedInstance() -> DataController {
if (dataController != nil) {
return dataController
}
dataController = DataController()
return dataController
}
}

Aquí es donde mi método de guardar es para guardar el contexto.

AppDelegate.swift

import UIKit
import CoreData
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
static var appDelegate: AppDelegate!
/// Returns application documents directory path
///
/// - returns: application documents directory path string
func applicationDocumentsDirectory() -> String {
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
print(paths[0])
return paths[0]
}
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
//Override point for customization after application launch.
AppDelegate.appDelegate = self
_ = applicationDocumentsDirectory();
return true
}
func applicationWillResignActive(_ application: UIApplication) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
}
func applicationDidEnterBackground(_ application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(_ application: UIApplication) {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(_ application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
func applicationWillTerminate(_ application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
// Saves changes in the application''s managed object context before the application terminates.
self.saveContext()
}
// MARK: - Core Data stack
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: "WorkOrders")
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 = DataController.sharedInstance().managedObjectContext
context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
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)")
}
}
}
}

Answer 4

No estoy seguro de cuál es su pregunta, pero debe eliminar el objeto de la instancia de NSManagedObjectContext. Entonces en tu función commitEditingStyle :

let moc = appDelegate.managedObjectContext // or something similar to get the managed object context
moc.delete(data) // your NSManagedObject

Answer 5

Para Xcode 8 y Swift 3.0. Si necesitamos ELIMINAR todos los datos de cualquier Tabla, debemos usar el código:

Archivo LoadStorage Class: también es compatible con iOS 9 e iOS 10 anteriores.

import UIKit
import CoreData
class localStorage: NSObject {
//MARK: - Up for iOS10 and above
@available(iOS 10.0, *)
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: "JJS_Connect")
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 () {
if #available(iOS 10.0, *) {
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)")
}
}
}
else {
}
}
//MARK: - Usp for iOS10 below
lazy var applicationDocumentsDirectory: NSURL = {
// The directory the application uses to store the Core Data store file. This code uses a directory named "com.razeware.HitList" in the application''s documents Application Support directory.
let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
return urls[urls.count-1] as NSURL
}()
lazy var managedObjectModel: NSManagedObjectModel = {
// The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
let modelURL = Bundle.main.url(forResource: "JJS_Connect", withExtension: "momd")!
return NSManagedObjectModel(contentsOf: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
// The persistent store coordinator for the application. This implementation creates and return a coordinator, having added 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.
// Create the coordinator and store
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.appendingPathComponent("JJS_Connect.sqlite")
var failureReason = "There was an error creating or loading the application''s saved data."
do {
try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
} catch {
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application''s saved data" as AnyObject?
dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?
dict[NSUnderlyingErrorKey] = error as NSError
let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
// Replace this with code to handle the error appropriately.
// abort() 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.
NSLog("Unresolved error /(wrappedError), /(wrappedError.userInfo)")
abort()
}
return coordinator
}()
lazy var managedObjectContext: NSManagedObjectContext = {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
let coordinator = self.persistentStoreCoordinator
var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
// MARK: - Creating NSManagedObject for saving data into table
func getContext() -> NSManagedObjectContext {
if #available(iOS 10.0, *) {
let context = self.persistentContainer.viewContext
return context
}else{
let context = self.managedObjectContext
return context
}
}
}

Que crear la clase DatabaseMaster y hacer funcionar:

 //MARK: - DELETE OPERATION FROM DB
func deleteFromAddressMaster() -> Void{
let request: NSFetchRequest<Address_master>
if #available(iOS 10.0, OSX 10.12, *) {
request = Address_master.fetchRequest()
} else {
request = NSFetchRequest(entityName: "Address_master")
}
do {
let results = try localStr.getContext().fetch(request)
for address in results {
print(" Deleted... /(address.group_id)")
localStr.getContext().delete(address)
}
} catch let error {
print(error.localizedDescription)
}
}

Address_master es el nombre de archivo de la Subclase. por favor defina

dejar localStr = localStorage ()

en el archivo DatabasMaster Class.

Answer 6

Para completar la respuesta de zisoft:

Debe guardar su contexto después de eliminar un objeto.

Entonces, la forma correcta sería:

// get your app managemenent context
let appDel:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
let context = self.appDel.managedObjectContext!
// remove your object
context.del(data)
// save your changes
context.save(nil)

Nota para verificar primero si hay reglas de eliminación (si tiene algún objeto relacionado)

Answer 7

let entityDescription =
NSEntityDescription.entity(forEntityName: "Contacts",
in: managedObjectContext)
let request: NSFetchRequest<Contacts> = Contacts.fetchRequest()
request.entity = entityDescription
if let result = try? managedObjectContext.fetch(request) {
for object in result {
do {
try managedObjectContext.delete(object)
txtName?.text = ""
txtAddress?.text = ""
txtPhone?.text = ""
Status?.text = "Contact Deleted"
txtName?.text = ""
}
catch let error {
Status?.text = error.localizedDescription
}
}
}