ios - 如何将项目从初始(一次)第一次 View Controller 传递到主视图 Controller 并使用核心数据保存该数据

Question

我已经在这个问题上工作了两天，遗憾的是我无法解决我的问题。我试图从我最初的一次性 View Controller 中取出一项并将其发送到我的主视图 Controller ，它将保存在主视图 Controller 中并在重新加载应用程序时出现在该 Controller 上。

这是我的“第一次” View Controller 的应用程序委托(delegate)代码

 func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    if UserDefaults.standard.bool(forKey: "firstTimer") {
    let storyBoard = UIStoryboard.init(name: "Main", bundle: nil)
    let mainView = storyBoard.instantiateViewController(withIdentifier: "MainViewControllerID")
        let nav = UINavigationController(rootViewController: mainView)
        nav.navigationBar.isHidden = true
        self.window?.rootViewController = nav
    }
    return true
}

容器和 saveContext 是默认的

import UIKit

import CoreData

class FirstTimeViewController: UIViewController {

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
 private var appDelegate = UIApplication.shared.delegate as! AppDelegate
private var player = [Player]()





@IBOutlet weak var nameTextField: UITextField!

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

// This View Controller will only be used once upon the first time the app is being used.

// MARK: Make func that prepares for segue on initial opening of app


override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "toMainViewController" {
        let mainViewController = segue.destination as! UINavigationController
        let destination = mainViewController.topViewController as! MainViewController
        if let newPlayer = self.nameTextField.text{
            destination.name.name = newPlayer
            destination.playerData.name = newPlayer
            saveItems()
        }
    }

}

@IBAction func continueButtonPressed(_ sender: UIStoryboardSegue) {
    UserDefaults.standard.set(true, forKey: "firstTimer")
    let mainPlayer = PlayerData()
    let player1 = Player(entity: Player.entity(), insertInto: context)
    player1.name = mainPlayer.name
    performSegue(withIdentifier: "toMainViewController", sender: self)
    saveItems()
}


func saveItems() {
    do {
    try context.save()
        print("File Successfully saved!")
    }catch {
       print("Error saving Context \(error)")
    }
}



// MARK: Function to Save and Load data??
/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    // Get the new view controller using segue.destination.
    // Pass the selected object to the new view controller.
}
*/

func loadItems() {
    let request = Player.fetchRequest() as NSFetchRequest<Player>
    do {
        player = try context.fetch(request)
        print("Info loaded")
    } catch {
        print("Error fetching data from context \(error)")
    }
}
}

MainViewController 正在发送信息。我只想发送一项并将其保存到该主视图 Controller 。

import UIKit
import Foundation
import CoreData

class MainViewController: UIViewController {
//set up model object, buttons, and labels
//    let player: Player!
let context = (UIApplication.shared.delegate as!          AppDelegate).persistentContainer.viewContext
private var appDelegate = UIApplication.shared.delegate as! AppDelegate
//    lazy var nameText = Player(context: context)
//    var playerInfo = [Player]()
lazy var player = [Player]()
let playerData = PlayerData()
var name = ""


@IBOutlet weak var playerName: UILabel!

@IBOutlet weak var currentLevel: UILabel!

@IBOutlet weak var xpCounter: UILabel!

@IBOutlet weak var playerProfileImage: UIImageView!



override func viewDidLoad() {
    super.viewDidLoad()

//        loadItems()
//        name = playerData.name
    if let nameOfPlayer = name.name {
        print("This is what we see: \(nameOfPlayer)")
    playerName.text = nameOfPlayer
    }
    appDelegate.saveContext()

}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
//        loadView()

}

@IBAction func menuButtonPressed(_ sender: Any) {

}

func loadItems() {
    let request = Player.fetchRequest() as NSFetchRequest<Player>
    do {
        player = try context.fetch(request)
        print("Info loaded")
    } catch {
        print("Error fetching data from context \(error)")
    }
}
// MARK : Add Name to Main View


// MARK : Add Xp To Main View

// MARK : Add UI Image to profile image view

// MARK:  (Optional) Create a 'Choose a task button to segue to the task tab'


// MARK: Program the Progress Bar to update on xp gained and reset on level up


// MARK: Function to Save and Load data??
}

如果需要数据源代码，我会根据要求添加。

谢谢!

Answer 1

代码错误。你应该多做检查