Supprimer les Données de Coredata Swift

Swift 3.0

Ci-dessous est le code pour supprimer le point et de recharger les données.

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()
}

Pas sûr de ce que votre question est, mais vous devez supprimer l'objet de la NSManagedObjectContext instance. Donc, dans votre commitEditingStyle fonction:

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

Aucune des réponses ci-dessus m'a aidé dans le cas que je suis en utilisant la Base de Données avec un FetchedResultsController pour une tableView. En tant que tel, ici, est mon de mise en œuvre pour gérer la suppression ci-dessous. Mon exemple utilise un exemple simple, supposons que vous souhaitez supprimer une photo de la glisser vers la gauche sur une table et en sélectionnant la valeur par défaut de l'option de suppression.

Swift 3 Solution pour FetchedResultsController Implementaitons

D'abord ajouter cette méthode du délégué pour l'affichage de la table pour permettre l'édition lorsque vous balayez la ligne.

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

}
}

Une fois que vous avez fait cela, assurez-vous que le fetchedResultsController a son délégué ensemble de votre contrôleur et de mise en œuvre de ces méthodes.

    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;
}
}

Le secret ici est d'obtenir l'accès à l'objet via le fetchedResultsController.méthode de l'objet

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

De cette façon, vous pouvez exécuter

context.delete(picture)

qui est intelligent à propos de la suppression NSManagedObjects.

Infos supplémentaires Liées à mon Application (Seulement lire ci-dessous si vous avez besoin de plus de détails)

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

Image+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?
}

Photos+CoreDataClass.swift

import Foundation
import CoreData
public class Pictures: NSManagedObject {
}

Le fichier ci-dessous est mon coreData pile gestionnaire.

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
}
}

C'est là que ma méthode d'enregistrement est pour la sauvegarde du contexte.

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)")
}
}
}
}