我创建了一个ToDo List应用程序.
我用tableView列出了任务.我使用自定义类进行单元格.在单元格内容中,我有一个标签和一个完成按钮.我已在代码中成功实现了完成按钮单击操作.它工作正常.
问题
当我单击完成按钮时,它会删除最后添加的任务.但不是点击的那个.当我重试单击完成按钮时,它不执行任何操作.如何解决此错误
GIF在下面添加,点击链接
实体类ToDo
进口基金会
导入CoreData
public class ToDo: NSManagedObject {
public override func awakeFromInsert() {
self.created = NSDate()
}
}
MainVC
import UIKit
import CoreData
class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, NSFetchedResultsControllerDelegate {
var controller: NSFetchedResultsController<ToDo>!
@IBOutlet weak var taskTextField: CustomTextField!
@IBOutlet weak var tableView: UITableView!
var toDo: ToDo!
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
// generateData()
attemptFetch()
}
// to give view to cell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ItemCell", for: indexPath) as! ItemCell
configureCell(cell: cell, indexPath: indexPath as NSIndexPath)
return cell
}
// custom function
func configureCell(cell: ItemCell, indexPath: NSIndexPath) {
let toDo = controller.object(at: indexPath as IndexPath)
// call the method on the ItemCell
cell.configureCell(toDo: toDo)
// done button click
cell.doneBtn.tag = indexPath.row
cell.doneBtn.addTarget(self, action: #selector(MainVC.donePressed), for: UIControlEvents.touchUpInside)
}
// when select a cell
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// it ensure it have object and atleast one object in there
if let objs = controller.fetchedObjects, objs.count > 0 {
let task = objs[indexPath.row]
performSegue(withIdentifier: "ItemDetailsVC", sender: task)
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ItemDetailsVC" {
if let destination = segue.destination as? ItemDetailsVC {
if let task = sender as? ToDo {
destination.taskDetails = task
}
}
}
}
// count of cells
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// we check here if any sections then take info of them and count
if let sections = controller.sections {
let sectionInfo = sections[section]
return sectionInfo.numberOfObjects
}
return 0
}
// column count
func numberOfSections(in tableView: UITableView) -> Int {
if let sections = controller.sections {
return sections.count
}
return 0
}
// give height of a cell
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 70
}
// fetching function
func attemptFetch() {
// create a fetch request with fetching Entity
let fetchRequest: NSFetchRequest<ToDo> = ToDo.fetchRequest()
// sorting area
let dateSort = NSSortDescriptor(key: "created", ascending: true)
fetchRequest.sortDescriptors = [dateSort]
let controller = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
controller.delegate = self
self.controller = controller
// actual fetching
do {
try controller.performFetch()
} catch {
let error = error as NSError
print("\(error)")
}
}
// when tableView changes this function starts listen for changes and
// it will handle that for you
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.beginUpdates()
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.endUpdates()
}
// this function will listen for when we make change
// insertion, deletion .. etc
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch type {
case.insert:
if let indexPath = newIndexPath {
tableView.insertRows(at: [indexPath], with: .fade)
}
break
case.delete:
if let indexPath = indexPath {
tableView.deleteRows(at: [indexPath], with: .fade)
}
break
case.update:
if let indexPath = indexPath {
let cell = tableView.cellForRow(at: indexPath)
//update the cell data
configureCell(cell: cell as! ItemCell, indexPath: indexPath as NSIndexPath)
}
break
case.move:
if let indexPath = indexPath {
tableView.deleteRows(at: [indexPath], with: .fade)
}
if let indexPath = newIndexPath {
tableView.insertRows(at: [indexPath], with: .fade)
}
break
}
}
@IBAction func addBtnPressed(_ sender: UIButton) {
if taskTextField.text != "" && taskTextField.text != nil {
toDo = ToDo(context: context)
if let task = taskTextField.text {
toDo.title = task
}
ad.saveContext()
taskTextField.text = ""
self.tableView.reloadData()
}
}
// done button
func donePressed() {
if toDo != nil {
context.delete(toDo)
ad.saveContext()
}
}
func generateData() {
let task = ToDo(context: context)
task.title = "alwin"
let task1 = ToDo(context: context)
task1.title = "rambo"
let task2 = ToDo(context: context)
task2.title = "monisha"
let task3 = ToDo(context: context)
task3.title = "wounderlist"
let task4 = ToDo(context: context)
task4.title = "presentation"
let task5 = ToDo(context: context)
task5.title = "roundup"
// to save data
ad.saveContext()
}
}
ItemDetailsVC
import UIKit
class ItemDetailsVC: UIViewController {
var taskDetails: ToDo?
@IBOutlet weak var detailsLbl: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// to clear the <DreamLIst to < only
if let topItem = self.navigationController?.navigationBar.topItem {
topItem.backBarButtonItem = UIBarButtonItem(title: "", style: UIBarButtonItemStyle.plain, target: nil, action: nil)
// this is execute when tap on an existing cell
if taskDetails != nil {
loadItemData()
}
}
}
func loadItemData() {
if let task = taskDetails {
detailsLbl.text = task.title
}
}
override func viewDidLayoutSubviews() {
detailsLbl.sizeToFit()
}
@IBAction func deletePressed(_ sender: UIBarButtonItem) {
if taskDetails != nil {
context.delete(taskDetails!)
ad.saveContext()
}
_ = navigationController?.popViewController(animated: true)
}
}
故事板,点击下面的链接
ItemCell
import UIKit
class ItemCell: UITableViewCell {
@IBOutlet weak var taskTitle: UILabel!
@IBOutlet weak var doneBtn: UIButton!
var toDo: ToDo?
func configureCell(toDo: ToDo) {
taskTitle.text = toDo.title
}
}
最佳答案 OK目前您正在将完成按钮的选择器设置到其容器(单元格)之外这通常是不好的做法,您使用ToDo配置单元格但不在单元格内部分配可选项,据说可以保留对单元格的引用ToDo.
在我看来,我会稍微改变这一点,以便您首先存储对ToDo的引用：
func configureCell(toDo: ToDo) {
self.toDo = toDo
taskTitle.text = toDo.title
}
现在在您的单元格上创建一个协议,然后使用ToDo和委托配置单元格,然后按下按钮告诉委托您的按钮被按下了相关的ToDo …
protocol ToDoCellDelegate: class {
func toDoCellButtonPressed(todo: ToDo?)
}
现在您的单元格配置为：
func configureCell(toDo: ToDo, delegate: ToDoCellDelegate) {
self.delegate = delegate
self.toDo = toDo
taskTitle.text = toDo.title
}
并向单元格中的委托添加一个引用：
weak var delegate: ToDoCellDelegate?
现在将按钮选择器更改为单元格内的func
func buttonPressed() {
self.delegate?.cellToDoButtonPressed(toDo: toDo)
}
然后在您的VC中,您符合在配置中传递self的委托并实现委托：
extension ItemDetailsVC: ToDoCellDelegate {
func toDoCellButtonPress(toDo: ToDo?) {
if let t = toDo {
//tell context to delete todo and remove cell.
}
}
}
