在我将 Core Data 与 FetchedResultsController 用于 tableView 的情况下，上述答案都没有帮助我。因此，这是我在下面处理删除的实现。我的示例使用了一个简单的示例，假设您要通过在表格上向左滑动并选择默认删除选项来删除图片。
用于 FetchedResultsController 实现的 Swift 3 解决方案
首先为表格视图添加这个委托方法，以便在您在行上滑动时允许编辑。
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
}
}
完成此操作后，请确保 fetchedResultsController 已将其委托设置为您的控制器并实现这些方法。
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;
}
}
这里的秘密是通过 fetchedResultsController.object 方法访问对象
let picture = self.fetchedResultsController.object(at: indexPath) as Pictures
这样就可以跑了
context.delete(picture)
删除 NSManagedObjects 很聪明。
与我的实施相关的额外信息（如果您需要更多详细信息，请阅读下文）
----------------------------------------------- ----------------------------------------
图片+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?
}
图片+CoreDataClass.swift
import Foundation
import CoreData
public class Pictures: NSManagedObject {
}
下面的文件是我的 coreData 堆栈处理程序。
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
}
}
这是我的保存方法用于保存上下文的地方。
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)")
}
}
}
}