【发布时间】：2021-11-16 01:45:24
【问题描述】：
我正在处理核心数据 crud 操作。我有 Person 对象，当用户单击添加 (+) 按钮时，用户可以添加人名，人名将显示在 tableview 中。当用户单击任何 tableView 单元格时，它会在警报文本字段中显示警报和当前点击单元格人员，并且用户可以编辑人员的姓名，但我的逻辑无法正常工作并且用户没有进行编辑。我还有一个问题，例如何时我运行的应用程序之前的用户记录没有显示，但它会在我进入新用户并获取所有之前的用户看到代码并提前指导我后显示。
ViewController 类：
@IBOutlet weak var tableView: UITableView!
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var items : [Person] = [] {
didSet{
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.delegate = self
self.tableView.dataSource = self
tableView.register(UINib(nibName: String(describing: StundentCell.self), bundle: .main), forCellReuseIdentifier: String(describing: StundentCell.self))
}
@IBAction func addPerson(_ sender: UIBarButtonItem) {
showAlert()
}
private func showAlert(_ title:String = "Add new Item", message: String = "what is your name"){
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
alertController.addTextField()
let subbmitBtn = UIAlertAction(title: "Add Person", style: .default) { (action) in
let textField = alertController.textFields![0]
let newPerson = Person(context:self.context)
newPerson.name = textField.text
newPerson.age = 20
newPerson.gender = "Male"
do {
try self.context.save()
}
catch{
}
self.fetchPerople()
}
alertController.addAction(subbmitBtn)
self.present(alertController, animated: true, completion: nil)
}
func fetchPerople(){
do{
self.items = try context.fetch(Person.fetchRequest())
}
catch{
}
}
}
extension ViewController: UITableViewDelegate,UITableViewDataSource{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
self.configurePersonCell(tableView, cellForRowAt: indexPath)
}
func configurePersonCell(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
guard let cell = tableView.dequeueReusableCell(withIdentifier: String(describing: StundentCell.self)) as? StundentCell else {return UITableViewCell()}
cell.studentData = items[indexPath.row]
cell.delete.tag = indexPath.row
cell.delete.addTarget(self, action: #selector(deleteRecord(sender:)), for: .touchUpInside)
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
var person = items[indexPath.row].name
let alertController = UIAlertController(title: "Edit Person", message: "Edit name", preferredStyle: .alert)
alertController.addTextField()
let alertField = alertController.textFields![0]
alertField.text = person
let saveBtn = UIAlertAction(title: "Save", style: .default) { (action) in
let getName = alertController.textFields![0]
person = getName.text
do{
try self.context.save()
}
catch{
}
self.fetchPerople()
}
alertController.addAction(saveBtn)
self.present(alertController, animated: true, completion: nil)
}
func gotoPersonDetails(personData:Person){
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 50
}
@objc func deleteRecord(sender: UIButton){
if items.count > 0{
let personRemove = self.items[sender.tag]
self.context.delete(personRemove)
do {
try self.context.save()
}
catch{
}
self.fetchPerople()
}
}
@IBOutlet weak var tableView: UITableView!
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var items : [Person] = [] {
didSet{
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.delegate = self
self.tableView.dataSource = self
tableView.register(UINib(nibName: String(describing: StundentCell.self), bundle: .main), forCellReuseIdentifier: String(describing: StundentCell.self))
}
@IBAction func addPerson(_ sender: UIBarButtonItem) {
showAlert()
}
private func showAlert(_ title:String = "Add new Item", message: String = "what is your name"){
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
alertController.addTextField()
let subbmitBtn = UIAlertAction(title: "Add Person", style: .default) { (action) in
let textField = alertController.textFields![0]
let newPerson = Person(context:self.context)
newPerson.name = textField.text
newPerson.age = 20
newPerson.gender = "Male"
do {
try self.context.save()
}
catch{
}
self.fetchPerople()
}
alertController.addAction(subbmitBtn)
self.present(alertController, animated: true, completion: nil)
}
func fetchPerople(){
do{
self.items = try context.fetch(Person.fetchRequest())
}
catch{
}
}
}
extension ViewController: UITableViewDelegate,UITableViewDataSource{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
self.configurePersonCell(tableView, cellForRowAt: indexPath)
}
func configurePersonCell(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
guard let cell = tableView.dequeueReusableCell(withIdentifier: String(describing: StundentCell.self)) as? StundentCell else {return UITableViewCell()}
cell.studentData = items[indexPath.row]
cell.delete.tag = indexPath.row
cell.delete.addTarget(self, action: #selector(deleteRecord(sender:)), for: .touchUpInside)
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
var person = items[indexPath.row].name
let alertController = UIAlertController(title: "Edit Person", message: "Edit name", preferredStyle: .alert)
alertController.addTextField()
let alertField = alertController.textFields![0]
alertField.text = person
let saveBtn = UIAlertAction(title: "Save", style: .default) { (action) in
//get the person name in alert text field
let getName = alertController.textFields![0]
//edit the name of the person object
person = getName.text
do{
try self.context.save()
}
catch{
}
self.fetchPerople()
}
alertController.addAction(saveBtn)
self.present(alertController, animated: true, completion: nil)
}
func gotoPersonDetails(personData:Person){
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 50
}
@objc func deleteRecord(sender: UIButton){
/* fro api calling or firebase for deleting the rows in tableview
if items.count > 0 {
items.remove(at:sender.tag)
}
*/
if items.count > 0{
let personRemove = self.items[sender.tag]
//remove the person
self.context.delete(personRemove)
//save the data
do {
try self.context.save()
}
catch{
}
//refetch the data
self.fetchPerople()
}
}
【问题讨论】：