Delete Data from Coredata Swift

Question

In my tableViewController I have the following. And I am trying to get delete an item to work.

var myData: Array = []

override func tableV         


        

Answer 1

For Xcode 8 and Swift 3.0. If we need to DELETE all data from any Table than we should use the code:

LoadStorage Class file: it also support 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'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
                }
            }
        }

Than Create DatabaseMaster class and make function:

    //MARK: - DELETE OPERATION FROM DB
        func deleteFromAddressMaster() -> Void{
            let request: NSFetchRequest
            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 Subclass file name. please define

let localStr = localStorage()

in DatabasMaster Class file.