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我是一個初學者,在iOS開發中很快。我面臨的問題是:我正在使用CoreData構建應用程序,該應用程序包含表格視圖和表格單元格。我無法解釋,因爲我缺乏知識,所以我分享了截圖。我看過其他問題,他們都沒有解決我的錯誤。 和我也爲AppDelegate的情況下這是tabelview RowInSection致命錯誤swift
@available(iOS 10.0, *)
let ad = UIApplication.shared.delegate as! AppDelegate
@available(iOS 10.0, *)
let context = ad.persistentContainer.viewContext
我對VC的代碼是
import UIKit
import CoreData
class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, NSFetchedResultsControllerDelegate {
@IBOutlet weak var tableViewmain: UITableView!
@IBOutlet weak var topSegment: UISegmentedControl!
var fetchResultControll: NSFetchedResultsController<Items>!
override func viewDidLoad() {
super.viewDidLoad()
tableViewmain.delegate = self
tableViewmain.dataSource = self
doFetch()
}
func configureCell (cell: ItemsCell, indexPath: IndexPath) {
let item = fetchResultControll.object(at: indexPath) // remember as here
cell.confugringCell(item: item)
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableViewmain.dequeueReusableCell(withIdentifier: "ItemsCell", for: indexPath) as! ItemsCell
configureCell(cell: cell, indexPath: indexPath)
return cell
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let sections = fetchResultControll.sections{
let sectionInfo = sections[section]
return sectionInfo.numberOfObjects
}
return 0
}
func numberOfSections(in tableView: UITableView) -> Int {
if let allSections = fetchResultControll.sections {
return allSections.count
}
return 0
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 150
}
func doFetch() {
let fetchRequest: NSFetchRequest<Items> = Items.fetchRequest()
let dateSrot = NSSortDescriptor(key: "created", ascending: false)
fetchRequest.sortDescriptors = [dateSrot]
if #available(iOS 10.0, *) {
let controller = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
do {
try controller.performFetch()
}
catch {
let err = error as NSError
print("\(err)")
}
} else {
// Fallback on earlier versions
}
}
//controler willchnge
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableViewmain.beginUpdates()
}
//controlerdidchnge
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableViewmain.endUpdates()
}
//controlerdidchangeanobject
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch(type) {
case .insert:
if let indexpath = newIndexPath {
tableViewmain.insertRows(at: [indexpath], with: .fade)
}
break
case .delete:
if let indexpath = indexPath {
tableViewmain.deleteRows(at: [indexpath], with: .fade)
}
break
case .update:
if let indexpath = indexPath {
let cell = tableViewmain.cellForRow(at: indexpath) as! ItemsCell
configureCell(cell: cell, indexPath: indexpath) // as used here
}
break
case .move:
if let indexpath = indexPath {
tableViewmain.deleteRows(at: [indexpath], with: .fade)
}
if let indexpath = newIndexPath {
tableViewmain.insertRows(at: [indexpath], with: .fade)
}
break
}
}
我希望你明白我..任何幫助將高度讚賞
fetchedResultsController初始化在哪裏?根據你的代碼它是'nil'並導致錯誤。 – vadian
顯示確切的行,你得到的錯誤 –