Delete data from Coredata Swift

Question

In my TableViewController, I have the following. And I'm trying to remove an item to work.

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 } 

Then, to try and remove, I have.

 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

Updating my encoding problem while performing data deletion in fast and summary files. This code I ended up with worked.

 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 } } 

EDIT Above for Swift 2.2 and 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 } } 

It was also necessary to fix these two lines of code.

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

Answer 2

Swift 3.0

Below is the code to delete an item and reload the data.

 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 3

To execute a response from zisoft:

You need to save your context after deleting the object.

So the correct way:

 // 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) 

Note to check if there are any deletion rules (if you have related objects)

Answer 4

Not sure what your question is, but you should remove the object from the NSManagedObjectContext instance. So, in your commitEditingStyle function:

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

Answer 5

For Xcode 8 and Swift 3.0. If we need to DELETE all data from any table, we must use the code:

LoadStorage class file: it also supports iOS 9 and iOS 10 above.

 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 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 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 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 } } } 

Then create the DatabaseMaster class and execute the function:

  //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 is the name of the subclass. please specify

let localStr = localStorage ()

in the DatabasMaster Class file.

Answer 6

None of the answers above helped me in using Core Data with the FetchedResultsController for a tableView . As such, here is my implementation for handling deletion below. My example uses a simple example, assuming you want to remove the image from scrolling left on the table and choose the default delete option.

Swift 3 Solution for FetchedResultsController Implementaitons

First add this delegate method to represent the table to allow editing when scrolling through a row.

 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 } } 

Once you do this, make sure that the fetchedResultsController has its own delegate set by your controller and that implements these methods.

  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; } } 

The secret here is to access the object using the fetchedResultsController.object method

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

So you can run

 context.delete(picture) 

which can remove NSManagedObjects.

Additional information related to my implementation (read below if you need additional information)

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

Photo + 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? } 

Pictures + CoreDataClass.swift

 import Foundation import CoreData public class Pictures: NSManagedObject { } 

Below is my coreData stack handler.

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 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 } } 

Here, my save method is designed to maintain context.

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 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 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 } } }