在 Swift 中编辑 TableViewCell 的内容列表

Question

我有一个TableViewController，其中包含使用CoreData 的数据条目列表。我也有ViewController 和UITextView，由Segue 链接到TableViewController。我已经完成了对项目的添加、保存和删除等操作。

现在我正在通过将选定的TableViewCell 链接到下一个ViewController 上的UITextView 进行编辑。我已经在ViewController.I 上创建了一个操作DONE，能够将数据从选定的单元格传递到下一个@987654330 的TextView @ 使用 Segue。

现在，我需要更新UITextView 上的编辑文本，方法是单击完成按钮返回TableViewController 的单元格，并将数据保存到CoreData。请提供真正的建议和建议....我是 Swift 新手，我在此处附上了我的代码。

import UIKit
import CoreData

class ToDoTableViewController: UITableViewController {
var listItems = [NSManagedObject]()

override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.add, target: self , action: #selector(ToDoTableViewController.addItem))
}

func addItem(){
let alertController = UIAlertController(title: "To Do Tasks Lists!!!!", message: "Write Down...", preferredStyle: .alert)
let confirmAction = UIAlertAction(title: "Confirm", style: UIAlertActionStyle.default, handler: ({
    (_) in
    if let field = alertController.textFields![0] as? UITextField {
        self.saveItem(itemToSave: (field.text!))
        self.tableView.reloadData()
    }
    }
))

let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: nil)
alertController.addTextField(configurationHandler: ({
    (textField) in
    textField.placeholder = "Type in Something!!!!"
}))

alertController.addAction(confirmAction)
alertController.addAction(cancelAction)
self.present(alertController, animated: true, completion: nil)
}

func saveItem(itemToSave : String){
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let entity = NSEntityDescription.entity(forEntityName: "ListEntity", in: managedContext)
let item = NSManagedObject(entity: entity!, insertInto: managedContext)
item.setValue(itemToSave, forKey: "item")
do {
    try managedContext.save()
    listItems.append(item)
}
catch {

    print("Error")
}
}

override func viewWillAppear(_ animated: Bool) {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ListEntity")

do{
    let results = try managedContext.fetch(fetchRequest)
    listItems = results as! [NSManagedObject]
}
catch {
    print("Error")
}
}

override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
return true
}

override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let managedContext = appDelegate.managedObjectContext
    let objectToDelete = listItems[indexPath.row]
    listItems.remove(at: indexPath.row)
    managedContext.delete(objectToDelete)
    tableView.deleteRows(at: [indexPath], with: .fade)
    do {
        try managedContext.save()
    }
    catch {
        print("Error")
    }
}
}

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

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell")! as UITableViewCell
let item = listItems[indexPath.row]
cell.textLabel?.text = item.value(forKey: "item") as! String?
cell.backgroundColor = UIColor.clear
return cell
}

func getIndexPathForSelectedCell() -> IndexPath?
{
var indexPath2:IndexPath?
if tableView.indexPathsForSelectedRows!.count > 0 {
    indexPath2 = tableView.indexPathsForSelectedRows![0]
}
return indexPath2
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "detailView")
{
    if let indexPath2 = getIndexPathForSelectedCell()
    {
        // here write code for move to next controller.
        let vc = segue.destination as! TextEditViewController
        //vc.FirstString =  listItems[(indexPath2 as NSIndexPath).row] as String

        let item = listItems[(indexPath2 as NSIndexPath).row]
        vc.FirstString = (item.value(forKey: "item") as! String?)!
    }
}
}

}


//TextEditViewController
import UIKit
import CoreData
class TextEditViewController: UIViewController {
@IBOutlet weak var textEdit: UITextView!
var FirstString = String()    

override func viewDidLoad() {
super.viewDidLoad()
textEdit.text = FirstString
print(self.FirstString)
}

override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}

}

Answer 1

将您的 CoreData 模型引用传递到下一个屏幕：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "detailView")
{
    if let indexPath2 = getIndexPathForSelectedCell()
    {
        // here write code for move to next controller.
        let vc = segue.destination as! TextEditViewController
        //vc.FirstString =  listItems[(indexPath2 as NSIndexPath).row] as String
        let item = listItems[(indexPath2 as NSIndexPath).row]
        vc.FirstString = (item.value(forKey: "item") as! String?)!
        vc.recentItem = item; //Like this. Create a recentItem refrence to your next controller of NSManagedObject or your custom core data modal.
    }
}
}

当您在TextEditViewController 中完成编辑后：

recentItem.item = "String" //Your updated string

let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let managedContext = appDelegate.managedObjectContext
do {
        try managedContext.save()
    }
    catch {
        print("Error")
    }

希望这会奏效...！！