我是使用Xcode和swift并且还在学习的新手。我无法将核心数据从实体传递到文本字段/标签，然后用户可以选择编辑和保存记录。我的目标是当用户从friendslistViewController.swift点击tableView中的单元格时，然后将它们带到editViewController.swift屏幕以编辑并保存记录。我想我需要实现prepareforsegue函数，但不确定如何？
friendsViewController.swift （初始数据输入）
//
// friendsViewController.swift
//
//
// Created by on 11/10/17.
// Copyright © 2017. All rights reserved.
//
import UIKit
import CoreData
class friendsViewController: UIViewController {
//OUTLETS
@IBOutlet weak var firstName: UITextField!
@IBOutlet weak var lastName: UITextField!
@IBOutlet weak var genderSegControl: UISegmentedControl!
@IBOutlet weak var ageStepper: UIStepper!
//AGECOUNT
@IBOutlet weak var ageLabel: UILabel!
@IBOutlet weak var address: UITextField!
var context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
//actions
@IBAction func ageStepperStep(_ sender: UIStepper) {
let step = Int(sender.value) // using an integer variable
ageLabel.text = String(step)
// label1.text = Int(sender.value).description
// another way without using any integer variable
}
// TEST GENDER
/*
var gender : String
if self.genderSegControl.selectedSegmentIndex == 0 {
gender = "male"
}
else {
gender = "female"
}
genderLabel.text! = gender
*/
//SAVE FRIEND BUTTON
@IBAction func saveFriendBtn(_ sender: Any) {
if firstName.text != "" && lastName.text != "" {
var gender : String?
if self.genderSegControl.selectedSegmentIndex == 0 {
gender = "male"
}
else {
gender = "female"
}
let newFriend = NSEntityDescription.insertNewObject(forEntityName: "Friends", into: context)
newFriend.setValue(self.firstName.text, forKey: "firstName")
newFriend.setValue(self.lastName.text, forKey: "lastName")
newFriend.setValue(self.address.text, forKey: "address")
newFriend.setValue(self.ageLabel.text, forKey: "age")
newFriend.setValue(gender, forKey: "gender")
/*let gender: String = genderSegControl.titleForSegment(at: genderSegControl.selectedSegmentIndex)!
*/
//SAVE THE CONTEXT
do {
try context.save()
}
catch{
print(error)
}
}
else {
print("please enter your first and last name!")
}
}
} //end class
friendslistViewController.swift （显示带有单元格的tableView的屏幕）
//
// friendslistViewController.swift
//
//
// Created by on 11/10/17.
// Copyright © 2017. All rights reserved.
//
import UIKit
import CoreData
class friendslistViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
/*
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
var DestViewController : editViewController = segue.destinationViewController as! editViewController
DestViewController.firstNameInput = name.firstName!
}
*/
//outlets
@IBOutlet weak var tableView: UITableView!
var userArray:[Friends] = []
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
self.fetchData()
self.tableView.reloadData()
// Do any additional setup after loading the view.
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return userArray.count
}
//DISPLAY LISTVIEW
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
//save first users data into array
let name = userArray[indexPath.row]
cell.textLabel!.text = name.firstName! + " " +
name.lastName! + ", " +
name.age! + ", " +
name.gender! + ", " +
name.address!
return cell
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
if editingStyle == .delete{
//delete a friend
let friend = userArray[indexPath.row]
context.delete(friend)
(UIApplication.shared.delegate as! AppDelegate).saveContext()
do{
userArray = try context.fetch(Friends.fetchRequest())
}catch{
print(error)
}
}
tableView.reloadData()
}
//fetch the data
func fetchData(){
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
do{
userArray = try context.fetch(Friends.fetchRequest())
}
//if error exists/catch it
catch{
print(error)
}
}
//actions
} //end class
editViewController.swift （处理编辑/保存的屏幕）
//
// editViewController.swift
//
//
// Created by on 15/10/17.
// Copyright © 2017. All rights reserved.
//
import UIKit
import CoreData
class editViewController: UIViewController {
@IBOutlet weak var firstName: UITextField!
@IBOutlet weak var lastName: UITextField!
@IBOutlet weak var ageLabel: UILabel!
@IBOutlet weak var address: UITextField!
var firstNameInput = String()
override func viewDidLoad() {
super.viewDidLoad()
firstName.text = firstNameInput
// Do any additional setup after loading the view.
}
}
答案 0 :(得分：0)
首先，您应该更改视图控制器的名称，以便它们都以大写字母（例如class FriendsViewController: UIViewController）开头，并对文件名执行相同的操作。
其次，你需要添加一个segue是正确的。您是否在Apple的文档中查看了func prepare(for segue: UIStoryboardSegue, sender: Any?)？
您需要在目标视图控制器（editViewController.swift）中使用可以为其分配Friend对象的变量。在prepare(for:sender:)方法中，您需要let destinationViewController = segue.destination as! EditViewController之类的内容。然后，您可以使用该destinationViewController变量访问目标视图控制器中的变量，并将对象分配给它。
了解你能走多远。
答案 1 :(得分：0)
friendslistViewController.swift //Change this to match your segue
private let showEditSegueID = "Edit Friend"
private var selectedIndexPath : IndexPath?
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
selectedIndexPath = indexPath
performSegue(withIdentifier: showEditSegueID, sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
switch segue.identifier {
case .some(showEditSegueID):
if let editViewController = segue.destination as? editViewController,
let selectedIndexPath = selectedIndexPath {
let friend = userArray[selectedIndexPath.row]
editViewController.friend = friend
}
default:
break
}
}
editViewController.swift weak var friend : Friends?