每次从coredata加载tableView时复制单元格

Question

视图显示CoreData中每条记录的重复行，每次重新加载时会不断增加。代码如下:当我添加记录时，我查看记录它会显示记录。然后我点击主页后，当我点击查看记录，我看到同一记录的副本。现在我有两条相同的记录。有人能帮我吗我认为问题出在表视图上这是我的表视图控制器代码

import UIKit
import CoreData
var Rec = [Records]()
class TableViewController: UITableViewController {
var firstLoad = true
func nondel() -> [Records]
{
var nodellist = [Records]()
for note in Rec
{
if(note.del == nil)
{
nodellist.append(note)
}
}
return nodellist
}
override func viewDidLoad() {
super.viewDidLoad()
if(firstLoad)
{
firstLoad = false
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let context:NSManagedObjectContext = appDelegate.persistentContainer.viewContext
let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Records")
do{
let results: NSArray = try context.fetch(request) as NSArray
for result in results {
let note = result as! Records
Rec.append(note)
}
}
catch
{
print("Fetch Failed")
}
}

}


override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "myCell") as! TableViewCell

let thisrec: Records!
thisrec = nondel()[indexPath.row]
cell.idLB.text = thisrec.id
cell.nameLB.text = thisrec.name
cell.lastLB.text = thisrec.last
cell.genderLB.text = thisrec.gender
cell.ageLB.text = thisrec.age
cell.addressLB.text = thisrec.address
return cell

}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return nondel().count
}
override func viewDidAppear(_ animated: Bool) {
tableView.reloadData()
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath){
self.performSegue(withIdentifier: "editNote", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if(segue.identifier == "editNote")
{
let indexPath = tableView.indexPathForSelectedRow!
let recDetail = segue.destination as? AddViewController
let selectedCell: Records!
selectedCell = nondel()[indexPath.row]
recDetail!.selectedCell = selectedCell
tableView.deselectRow(at: indexPath, animated: true)
}
}
}

Answer 1

你的代码太麻烦了。

• 首先，永远不要在任何类之外声明数据源。
• 其次，永远不要使用函数来构建数组作为表视图的数据源。
• 第三个firstRun是没有意义的，因为viewDidLoad无论如何只被调用一次。
• 第四，而不是手动过滤接收到的记录对获取请求
应用谓词

此外，强烈建议将核心数据实体命名为单数形式(Record)，并使用该实体的特定通用获取请求。

class TableViewController: UITableViewController {
var records = [Record]()

override func viewDidLoad() {
super.viewDidLoad()

let appDelegate = UIApplication.shared.delegate as! AppDelegate
let context = appDelegate.persistentContainer.viewContext
let request : NSFetchRequest<Record> = Record.fetchRequest()
request.predicate = NSPredicate(format: "del != nil")
do {
records = try context.fetch(request)
} catch { print("Fetch Failed", error) }
}        

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "myCell") as! TableViewCell

let thisrec = records[indexPath.row]
cell.idLB.text = thisrec.id
cell.nameLB.text = thisrec.name
cell.lastLB.text = thisrec.last
cell.genderLB.text = thisrec.gender
cell.ageLB.text = thisrec.age
cell.addressLB.text = thisrec.address
return cell
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return records.count
}
...