使用FRC Swift 3更改CoreData后，TableView不会更新（reloadData）

我已经更新了这个问题，因为我发现了这个问题的另一个关键。 似乎当我向CoreData添加内容时，即使我可以打印出CoreData已保存的对象，tableview也不会重新加载数据。 所以我知道数据是正确的，但函数func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell永远不会被调用。

值得注意的是，如果我停止应用程序并重新打开它，表视图将显示正确数量的单元格和信息。 所以似乎数据只在初始构建时加载属性。

我有一个UITableView ，由CoreData填充，也使用FetchedResultsController 。 我添加了FRC委托方法，我试图强制使用tableView.reloadData()方法，但这似乎不起作用。 如果我停止构建并重建项目，数据会显示出来。

以下是我使用的委托方法：

  func controllerWillChangeContent(_ controller: NSFetchedResultsController) { tableView.beginUpdates() } func controller(_ controller: NSFetchedResultsController, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) { switch type { case .insert: tableView.insertRows(at: [newIndexPath!], with: .automatic) case .delete: tableView.deleteRows(at: [indexPath!], with: .automatic) case .update: tableview.reloadData() case .move: tableView.deleteRows(at: [indexPath!], with: .automatic) tableView.insertRows(at: [newIndexPath!], with: .automatic) } } func controllerDidChangeContent(_ controller: NSFetchedResultsController) { tableView.endUpdates() } 

当我回到这个视图时，我想强制tableview重新加载它的数据。

ViewwillAppear方法：

 override func viewWillAppear(_ animated: Bool) { // load the data let fetchRequest: NSFetchRequest = Person.fetchRequest() fetchRequest.predicate = NSPredicate(format:"[e-mail] >= 0") let sort = NSSortDescriptor(key: #keyPath(Person.name), ascending: true) fetchRequest.sortDescriptors = [sort] positiveFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: coreDataStack.managedContext, sectionNameKeyPath: nil, cacheName: nil) do{ try positiveFetchedResultsController.performFetch() }catch let error as NSError{ print("Fetching error: \(error), \(error.userInfo)") } let negativFetchRequest: NSFetchRequest = Person.fetchRequest() negativFetchRequest.predicate = NSPredicate(format:"[e-mail] < 0") let negativeSort = NSSortDescriptor(key: #keyPath(Person.name), ascending: true) negativFetchRequest.sortDescriptors = [negativeSort] negativeFetchedResultsController = NSFetchedResultsController(fetchRequest: negativFetchRequest, managedObjectContext: coreDataStack.managedContext, sectionNameKeyPath: nil, cacheName: nil) do{ try negativeFetchedResultsController.performFetch() }catch let error as NSError{ print("Fetching error: \(error), \(error.userInfo)") } positiveFetchedResultsController.delegate = self negativeFetchedResultsController.delegate = self print("\(positiveFetchedResultsController.fetchedObjects!.count) positive fetch count") //print("\(positiveFetchedResultsController.fetchedObjects![0].statement!.count) positive statements count") print("\(negativeFetchedResultsController.fetchedObjects!.count) negative fetch count") //print("\(negativeFetchedResultsController.fetchedObjects![0].statement!.count) negative statements count") tableView.reloadData() } 

这是我的cellForRowAt方法：

  func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: "personCell", for: indexPath) as! PersonTableViewCell switch(indexPath.section) { case 0: //print("this is section 0") let person = positiveFetchedResultsController.object(at: indexPath) cell.personName.text = person.name //print("\(person.name!) is the name") //print("\(person.statement!.count) postive person statement count") if(person.statement!.count == 0){ print("default") cell.statementAmount.text = "$0.00" } else{ //print("\(person.name!) has \(person.statement!.count) statement count") let amountTotal = person.value(forKeyPath: "[e-mail]") as? Decimal //print("\(amountTotal!) this is the total") cell.statementAmount.text = convertStringToDollarString(amountToConvert: String(describing: amountTotal!)) } case 1: print("this is section 1") //print("\(negativeFetchedResultsController.object(at: [indexPath.row,0])) objects fetched") //print("\(indexPath.section) section number") //print("\(indexPath.row) row number") let person = negativeFetchedResultsController.fetchedObjects![indexPath.row] cell.personName.text = person.name print("\(person.name!) is the name") print("\(person.statement!.count) negative person statement count") if(person.statement!.count == 0){ cell.statementAmount.text = "$0.00" } else{ //print("\(person.name!) has \(person.statement!.count) statement count") let amountTotal = person.value(forKeyPath: "[e-mail]") as? Decimal print("\(amountTotal!) this is the total") cell.statementAmount.text = String(describing: amountTotal!) cell.statementAmount.text = convertStringToDollarString(amountToConvert: String(describing: amountTotal!)) } cell.backgroundColor = Styles.redColor(); let bgColorView = UIView() bgColorView.backgroundColor = Styles.darkRedColor() cell.selectedBackgroundView = bgColorView default: cell.personName.text = "hello" } return cell } 

Answer 1

也许试试这个：

 override func viewDidAppear(_ animated: Bool) { super.viewDidAppear(animated) self.tableView.reloadData() } 

Answer 2

• 为此，您可以在调用table reloadData之前在viewWillAppear函数中添加fetchedResultsController.delegate = nil。

 override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) fetchedResultsController.delegate = nil self.tableView.reloadData() }