如何删除表视图核心数据中的行。斯威夫特3
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我一直在研究如何从表视图中删除数据在Core Data中的行。我找不到任何可以帮助我处理代码的在线内容。我是Core Data的新手，所以我对它并不是很了解。
提前致谢
这是我的代码
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else { return}
let managedContext = appDelegate.persistentContainer.viewContext
let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "OfficialPT")
fetchRequest.sortDescriptors = [NSSortDescriptor(key:"createdAt",ascending:false)]
do {
AirForceDatabase = try managedContext.fetch(fetchRequest)
} catch let error as NSError {
print("Could not fetch. (error), (error.userInfo)")
}
}
func SideMenus ()
{
if revealViewController() != nil {
MenuButton.target = revealViewController()
MenuButton.action = #selector(SWRevealViewController.revealToggle(_:))
revealViewController().rearViewRevealWidth = 275
revealViewController().rightViewRevealWidth = 160
// profileButton.target = revealViewController()
// profileButton.action = #selector(SWRevealViewController.rightRevealToggle(_:))
view.addGestureRecognizer(self.revealViewController().panGestureRecognizer())
}
}
}
扩展HistoryPTViewController：UITableViewDataSource {
func tableView(_ tableView: UITableView,
numberOfRowsInSection section: Int) -> Int {
return AirForceDatabase.count
}
func tableView(_ tableView: UITableView,
cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let cell = tableView.dequeueReusableCell(withIdentifier: "Cell",for: indexPath) as? HistoryPTTableViewCell {
let person = AirForceDatabase[indexPath.row]
cell.OfficialAbsLbl!.text = person.value(forKeyPath: "officialAbs")! as? String
cell.OfficialPushLbl!.text = person.value(forKeyPath: "officialPush")! as? String
cell.OfficialSitLbl!.text = person.value(forKeyPath: "officialSit")! as? String
cell.OfficialRunLbl!.text = person.value(forKeyPath: "officialRun")! as? String
cell.officialTotal!.text = person.value(forKeyPath: "totalScore")! as? String
cell.officialdateCreated.text = person.value(forKeyPath: "createdAt")! as? String
return cell
}
return UITableViewCell()
}
扩展HistoryPTViewController：UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
let person = AirForceDatabase[indexPath.row]
//Convert String to Double
if let score = person.value(forKeyPath: "totalScore")! as? String, let doubleScore = Double(score) {
officialTotalScore = doubleScore
//officialTotalScore = Double(score)
print("Score (officialTotalScore)")
}
var createdat :String!
CompostiveLbl.text = "Composite Score:
(officialTotalScore)%"
createdat = person.value(forKeyPath: "createdAt")! as? String
print(createdat + "CREATED")
if officialTotalScore >= 90 {
print("Excellent")
officialFinalScoreLbl.text = "Fitness Level:
Excellent"
}else if officialTotalScore >= 75 && officialTotalScore <= 89.9 {
print("Composite Score: Satisfactory")
officialFinalScoreLbl.text = "Fitness Level:
Satisfactory"
}else if officialTotalScore <= 75 {
print("Composite Score: Unsatisfactory")
officialFinalScoreLbl.text = "Fitness Level:
Unsatisfactory"
}
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = DateFormatter.Style.long
dateFormatter.dateFormat = "yyyy-MM-dd"
let convertedDate = dateFormatter.date(from: createdat)
dateFormatter.dateFormat = "MMM dd yyyy"
let date = dateFormatter.string(from: convertedDate!)
NextPTLbl.text = "Test Date:
" + date
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
let person = AirForceDatabase[indexPath.row]
if editingStyle == .delete {
}
}
答案
每当tableview处理Core Data时，你应该总是使用“NSFetchedResultsController”，因为构建了“NSFetchedResultsController”，记住了tableView。
它提供了有助于处理tableView的功能
- 与UITableViewDelegate和UITableviewdatasource协议一起，采用/符合“NSFetchedResultsControllerDelegate”协议。
- 然后实现其3种方法从核心数据中删除记录。并且不要重新查看tableview。 NSFetchedResultsController会处理它。
例如。让我们从核心数据加载数据（实体名称=电影）
var fetchedResultsController: NSFetchedResultsController<Movie>
override func viewDidLoad()
{
super.viewDidLoad()
loadData()
}
func loadData()
{
fetchedResultController = getMovies(managedObjectContext: self.coreData.persistentContainer.viewContext)
fetchedResultController.delegate = self
}
func getMovies(managedObjectContext: NSManagedObjectContext) -> NSFetchedResultsController<Movie>
{
let fetchedResultController: NSFetchedResultsController<Movie>
let request: NSFetchRequest<Movie> = Movie.fetchRequest()
let formatSort = NSSortDescriptor(key: "format", ascending: false)
let nameSort = NSSortDescriptor(key: "title", ascending: true)
request.sortDescriptors = [formatSort, nameSort]
fetchedResultController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: managedObjectContext, sectionNameKeyPath: "format", cacheName: "MyMovieLibrary")
do
{
try fetchedResultController.performFetch()
}
catch
{
fatalError("Error in fetching records")
}
return fetchedResultController
}
// MARK： - 表视图数据源
override func numberOfSections(in tableView: UITableView) -> Int
{
if let sections = fetchedResultController.sections
{
return sections.count
}
return 0
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
if let sections = fetchedResultController.sections
{
let currentSection = sections[section]
return currentSection.numberOfObjects
}
return 0
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell = tableView.dequeueReusableCell(withIdentifier: "movieCell", for: indexPath) as! MovieTableViewCell
let movie = fetchedResultController.object(at: indexPath)
cell.configureCell(movie: movie)
return cell
}
从核心数据中删除记录
// Override to support editing the table view.
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath)
{
let managedObjectContext = coreData.persistentContainer.viewContext
if editingStyle == .delete
{
movieToDelete = fetchedResultController.object(at: indexPath)
let confirmDeleteAlertController = UIAlertController(title: "Remove Movie", message: "Are you sure you would like to delete "(movieToDelete!.title!)" from your movie library?", preferredStyle: UIAlertControllerStyle.actionSheet)
let deleteAction = UIAlertAction(title: "Delete", style: UIAlertActionStyle.default, handler: { [weak self] (action: UIAlertAction) -> Void in
managedObjectContext.delete((self?.movieToDelete!)!)
self?.coreData.saveContext()
self?.movieToDelete = nil
})
let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: { [weak self] (action: UIAlertAction) -> Void in
self?.movieToDelete = nil
})
confirmDeleteAlertController.addAction(deleteAction)
confirmDeleteAlertController.addAction(cancelAction)
present(confirmDeleteAlertController, animated: true, completion: nil)
}
}
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>)
{
tableView.beginUpdates()
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?)
{
switch type
{
case NSFetchedResultsChangeType.delete:
print("NSFetchedResultsChangeType.Delete detected")
if let deleteIndexPath = indexPath
{
tableView.deleteRows(at: [deleteIndexPath], with: UITableViewRowAnimation.fade)
}
case NSFetchedResultsChangeType.insert:
print("NSFetchedResultsChangeType.Insert detected")
case NSFetchedResultsChangeType.move:
print("NSFetchedResultsChangeType.Move detected")
case NSFetchedResultsChangeType.update:
print("NSFetchedResultsChangeType.Update detected")
tableView.reloadRows(at: [indexPath!], with: UITableViewRowAnimation.fade)
}
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>)
{
tableView.endUpdates()
}
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