我有自定义单元格并使用核心数据，单元格未更新。 起初我使用Manual / None Codegen选项在。 xcdatamodeId 创建了一些实体。该项目不会构建，并会给我这个错误：
/ # docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ab192edf5872 luisbebop/echo-server "/opt/echo-server/..." 2 minutes ago Up About a minute 0.0.0.0:8800->8800/tcp echo-server
/ # netstat -nltup
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
在我为我的模型生成的类文件并删除了所有 @objc（Item）行之后，项目已经构建，但模拟器的单元格中没有任何内容。自定义单元格有一个标识符，用于 cellForRowAt 函数的代码中，我也生成测试数据，我可以像这样访问 AppDelegate
'An NSManagedObject of class 'DreamLister.Item' must have a valid NSEntityDescription.'编辑：在建议将codegen选项更改为类定义后，构建失败并出现Swift编译错误：
命令：let ad = UIApplication.shared.delegate as! AppDelegate
let context = ad.persistentContainer.viewContext
这是我的控制器的代码
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 1ItemCell的代码
import UIKit
import CoreData
class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, NSFetchedResultsControllerDelegate {
@IBOutlet weak var tableView: UITableView!
@IBOutlet weak var segment: UISegmentedControl!
var controller: NSFetchedResultsController<Item>!
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
generateTestData()
attemptFetch()
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ItemCell", for: indexPath) as! ItemCell
configureCell(cell: cell, indexPath: indexPath as NSIndexPath)
return cell
}
func configureCell(cell: ItemCell, indexPath: NSIndexPath) {
let item = controller.object(at: indexPath as IndexPath)
cell.configureCell(item: item)
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if let objs = controller.fetchedObjects , objs.count > 0 {
let item = objs[indexPath.row]
performSegue(withIdentifier: "ItemDetailsVC", sender: item)
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ItemDetailsVC" {
if let destination = segue.destination as? ItemDetailsVC {
if let item = sender as? Item {
destination.itemToEdit = item
}
}
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let sections = controller.sections {
let sectionInfo = sections[section]
return sectionInfo.numberOfObjects
}
return 0
}
func numberOfSections(in tableView: UITableView) -> Int {
return 0
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 150
}
func attemptFetch() {
let fetchRequest: NSFetchRequest<Item> = Item.fetchRequest()
let dateSort = NSSortDescriptor(key: "created", ascending: false)
fetchRequest.sortDescriptors = [dateSort]
let controller = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
controller.delegate = self
self.controller = controller
do {
try controller.performFetch()
} catch {
let error = error as NSError
print("\(error)")
}
}
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.beginUpdates()
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.endUpdates()
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch(type) {
case.insert:
if let indexPath = newIndexPath {
tableView.insertRows(at: [indexPath], with: .fade)
}
break
case.delete:
if let indexPath = indexPath {
tableView.deleteRows(at: [indexPath], with: .fade)
}
break
case.update:
if let indexPath = indexPath {
let cell = tableView.cellForRow(at: indexPath) as! ItemCell
configureCell(cell: cell, indexPath: indexPath as NSIndexPath)
}
break
case.move:
if let indexPath = indexPath {
tableView.deleteRows(at: [indexPath], with: .fade)
}
if let indexPath = newIndexPath {
tableView.insertRows(at: [indexPath], with: .fade)
}
break
}
}
func generateTestData() {
let item = Item(context: context)
item.title = "MacBook Pro"
item.price = 1800
item.details = "I can't wait until the September event, I hope they release new MPBs"
let item2 = Item(context: context)
item2.title = "Bose Headphones"
item2.price = 300
item2.details = "But man, its so nice to be able to block out everyone with the noise canceling tech."
let item3 = Item(context: context)
item3.title = "Tesla Model S"
item3.price = 110000
item3.details = "Oh man this is a beautiful car. And one day, I willl own it"
ad.saveContext()
}
}
和核心数据生成文件的代码
物品+ CoreDataClass.swift
import UIKit
class ItemCell: UITableViewCell {
@IBOutlet weak var thumb: UIImageView!
@IBOutlet weak var title: UILabel!
@IBOutlet weak var price: UILabel!
@IBOutlet weak var details: UILabel!
func configureCell(item: Item) {
self.title.text = item.title
self.price.text = "$\(item.price)"
self.details.text = item.details
}
}
物品+ CoreDataProperties.swift
import Foundation
import CoreData
public class Item: NSManagedObject {
public override func awakeFromInsert() {
super.awakeFromInsert()
self.created = NSDate()
}
}
任何想法或想法？ 在此先感谢。
答案 0 :(得分：0)
在核心数据文件中选择“实体”和“选择Codegen”选项以进行类别定义并运行并查看
答案 1 :(得分：0)
我再次删除并创建了核心数据的生成文件，并且我还将MainVC上这两个函数的return语句从零返回到此。
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let sections = controller.sections {
let sectionInfo = sections[section]
return sectionInfo.numberOfObjects
} else {
return 0
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}