首先我来自法国，很抱歉我的英语。
其次，我是开发新手，我已经开发了一个用于添加数据的代码，并在使用核心数据显示它们之后。它有效。确定
但是在我想要更新但遇到问题后，我不知道为什么无法更新我的值。出现错误:“ fatal error :在解包可选值时意外发现 nil”
自 1 周以来我已经尝试了很多解决方案，但找不到问题。谢谢如果有人可以帮助我!即使有一点帮助:)
这是我的代码(swift 2.3):
在表格 View 中显示:
import UIKit
import CoreData
class ProduitTableViewController: UITableViewController {
@IBOutlet var table: UITableView!
var produits = [NSManagedObject]()
func refreshStories(refreshControl: UIRefreshControl) {
produits.removeAll()
fetchData()
self.table.reloadData()
refreshControl.endRefreshing()
}
override func viewDidLoad() {
super.viewDidLoad()
self.fetchData()
self.table.addSubview(self.refreshControl!)
self.refreshControl?.addTarget(self, action: #selector(ProduitTableViewController.refreshStories(_:)), forControlEvents: UIControlEvents.ValueChanged)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func fetchData() {
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
//2
let fetchRequest = NSFetchRequest(entityName: "Produits")
let sort = NSSortDescriptor(key:"dateAjout", ascending:true)
fetchRequest.sortDescriptors = [sort]
//3
do {
let results = try managedContext.executeFetchRequest(fetchRequest)
produits = results as! [NSManagedObject]
} catch let error as NSError {
print("Donnees non recu \(error), \(error.userInfo)")
}
}
// MARK: - Table view data source
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return self.produits.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell")
let produit = produits[indexPath.row]
cell!.textLabel!.text = produit.valueForKey("nom") as? String
/*
let id = produit.valueForKey("id") as? String
let date = produit.valueForKey("date") as? NSDate
let localNotification = UILocalNotification()
localNotification.userInfo = ["id" : id!]
localNotification.soundName = UILocalNotificationDefaultSoundName
localNotification.alertBody = "expiré"
localNotification.fireDate = date
UIApplication.sharedApplication().scheduleLocalNotification(localNotification)
UIApplication.sharedApplication().applicationIconBadgeNumber += 1
*/
return cell!
}
override func tableView(tableView: UITableView, editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]? {
let supprimer = UITableViewRowAction(style: .Normal, title: "Suppr.") { action, index in
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let moc = appDelegate.managedObjectContext
// 3
moc.deleteObject(self.produits[indexPath.row])
appDelegate.saveContext()
// 4
self.produits.removeAtIndex(indexPath.row)
tableView.reloadData()
}
supprimer.backgroundColor = UIColor.redColor()
let update = UITableViewRowAction(style: .Normal, title: "Modifier") { action, index in
}
update.backgroundColor = UIColor.blueColor()
return [supprimer]
}
override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
// the cells you would like the actions to appear needs to be editable
return true
}
override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
if segue.identifier == "showDetail" {
if let destination = segue.destinationViewController as? DetailViewController {
let row = table.indexPathForSelectedRow?.row
let produit = produits[row!]
let nom = produit.valueForKey("nom") as? String
let id = produit.valueForKey("id") as? String
let detail = produit.valueForKey("detail") as? String
let date = produit.valueForKey("date") as? NSDate
let time = date
let formatter = NSDateFormatter()
formatter.dateFormat = "dd-MM-YY HH:mm"
let formatteddate = formatter.stringFromDate(time!)
destination.dataNom = nom!
destination.dataId = id!
destination.dataDetail = detail!
destination.dataDate = formatteddate
}
}
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
if table.cellForRowAtIndexPath(indexPath) != nil {
self.performSegueWithIdentifier("showDetail", sender: self)
}
}
}
显示单元格的详细信息:
import CoreData
import UIKit
class DetailViewController: UIViewController {
@IBOutlet var Label: UILabel!
@IBOutlet var Detail: UITextView!
@IBOutlet weak var Date: UILabel!
@IBOutlet weak var Id: UILabel!
var dataNom = ""
var dataDetail = ""
var dataDate = ""
var dataId = ""
override func viewDidLoad() {
super.viewDidLoad()
Label.text = dataNom
Detail.text = dataDetail
Date.text = dataDate
Id.text = dataId
// Do any additional setup after loading the view
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
if segue.identifier == "ModifierDetail" {
if let destination = segue.destinationViewController as? ModifierViewController {
destination.modifierNom = dataNom
destination.modifierId = dataId
destination.modifierDetail = dataDetail
destination.modifierDate = dataDate
}
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
}
*/
}
最后一个更新/修改我的详细信息:
import UIKit
import CoreData
class ModifierViewController: UIViewController {
@IBOutlet weak var Nom: UITextField!
@IBOutlet weak var Detail: UITextView!
@IBOutlet weak var Date: UITextField!
var Produits: NSManagedObject!
var managedContext: NSManagedObjectContext!
var modifierNom = ""
var modifierDetail = ""
var modifierDate = ""
var modifierId = ""
override func viewDidLoad() {
super.viewDidLoad()
Nom.text = modifierNom
Detail.text = modifierDetail
Date.text = modifierDate
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func Annuler(sender: UIBarButtonItem) {
navigationController?.popViewControllerAnimated(true)
}
@IBAction func Modifier(sender: UIButton) {
let fetchRequest = NSFetchRequest(entityName:"Produits")
fetchRequest.predicate = NSPredicate(format: "nom = %@", modifierNom)
do {
let list = try managedContext.executeFetchRequest(fetchRequest) as! [Produit]
if list.count == 0 // Check notificationId available then not save
{
let newManagedObject = NSEntityDescription.insertNewObjectForEntityForName("Produits", inManagedObjectContext: managedContext)
newManagedObject.setValue(modifierNom, forKey: "nom")
}
// success ...
} catch let error as NSError {
// failure
print("Fetch failed: \(error.localizedDescription)")
}
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
}
*/
}
我已经创建了另一个文件:
import Foundation
import CoreData
@objc(Produit)
class Produit: NSManagedObject {
@NSManaged var nom:String!
}
最佳答案
正如您在评论中提到的，此行导致崩溃:
let list = try managedContext.executeFetchRequest(fetchRequest) as! [Produit]
该行并不安全，因为您不知道转换为 [Prodiut] 是否始终会成功。
一般来说，当您不 1000% 知道它会发生时，您永远不应该强制转换 (as!) 或强制解包 (!) 某些内容成功。
为了安全地施放，您可以使用guard:
guard let list = try managedContext.executeFetchRequest(fetchRequest) as! [Produit] else {
//do some error handling here and then return
return
}
之后，您就可以安全地使用list了。
了解什么是 optional 以及如何安全地处理它们而不导致崩溃非常重要。
关于swift - 无法使用核心数据更新值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40807985/