ios - 设置当前为 "get-only"的属性值的最佳方法

Question

我有一个名为 ConferenceResultsTableViewCell 的 UITableViewCell 子类。这是它的代码:

import Foundation
import UIKit
import os.log

class ConferenceResultsTableViewCell: UITableViewCell {

    public var game: Game {

        get {
            guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
                fatalError("Could not get appDelagate in ConferenceResultsTableViewCell.swift")
            }
            let managedContext = appDelegate.persistentContainer.viewContext

            var contestantsStrArray = [String]()
            guard let contestant1 = gameWinnerControl.titleForSegment(at: 0) else {
                os_log("Could not unwrap contestant1 in ConferenceResultsTableViewCell.swift", log: OSLog.default, type: .debug)
                return Game.newGame(context: managedContext, contestants: nil, winner: nil, confidence: nil, conferences: nil)
            }
            guard let contestant2 = gameWinnerControl.titleForSegment(at: 1) else {
                os_log("Could not unwrap contestant2 in ConferenceResultsTableViewCell.swift", log: OSLog.default, type: .debug)
                return Game.newGame(context: managedContext, contestants: nil, winner: nil, confidence: nil, conferences: nil)
            }
            contestantsStrArray.append(contestant1)
            contestantsStrArray.append(contestant2)
            let winnerStr = contestantsStrArray[gameWinnerControl.selectedSegmentIndex]
            guard let confidenceStr = confidenceTextField.text else {
                os_log("Could not unwrap confidenceStr in ConferenceResultsTableViewCell.swift", log: OSLog.default, type: .debug)
                return Game.newGame(context: managedContext, contestants: contestantsStrArray, winner: winnerStr, confidence: nil, conferences: nil)
            }
            return Game.newGame(context: managedContext, contestants: contestantsStrArray, winner: winnerStr, confidence: Int(confidenceStr), conferences: nil)
        }

    }

    @IBOutlet weak var gameWinnerControl: UISegmentedControl!
    @IBOutlet weak var confidenceTextField: UITextField!
    @IBOutlet weak var confidenceAverageAllUsersLabel: UILabel!

}

此单元格应该有一个名为 game 的属性，其中包含将显示的一些信息。这是 Game.swift:

import Foundation
import CoreData

class Game: NSManagedObject {

    @NSManaged var contestants: [String]
    @NSManaged var winner: String
    @NSManaged var confidence: Int
    @NSManaged var conferences: [String]

}

extension Game {

    public static func newGame(context: NSManagedObjectContext, contestants: [String]?, winner: String?, confidence: Int?, conferences: [Conference]?) -> Game {

        let newGame = Game(context: context)

        if let contestants = contestants {
            newGame.contestants = contestants
        } else {
            newGame.contestants = ["", ""]
        }
        if let winner = winner {
            newGame.winner = winner
        } else {
            newGame.winner = ""
        }
        if let confidence = confidence {
            newGame.confidence = confidence
        } else {
            newGame.confidence = 0
        }
        if let conferences = conferences {
            newGame.conferences.removeAll()
            for conference in conferences {
                newGame.conferences.append(Conference.getStringValue(conference: conference))
            }
//            newGame.conferences = conferences.map({ Conference.getStringValue(conference: $0) })
        } else {
            newGame.conferences.removeAll()
            newGame.conferences.append("CAA")
        }

        return newGame

    }

}

我的问题是这个 game 变量当前是“仅获取”的，因此我无法从 ConferenceResultsTableViewController.tableView(cellForRowAt:) 设置游戏的值。以下是该方法的代码，该方法尝试为 game 变量设置单元格的值:

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        guard let cell = tableView.dequeueReusableCell(withIdentifier: CONFERENCE_RESULTS_CELL_IDENTIFIER, for: indexPath) as? ConferenceResultsTableViewCell else {
            fatalError("The dequeued cell is not an instance of ConferenceResultsTableViewCell.")
        }
        guard let game = self.gamesToBeShown[safe: indexPath.row] else {
            os_log("Could not unwrap game for indexPath in ConferenceResultsTableViewController.swift", log: OSLog.default, type: .default)
            self.tableView.reloadData()
            return ConferencesTableViewCell()
        }

        cell.game = game
        cell.gameWinnerControl.insertSegment(withTitle: game.contestants[0], at: 0, animated: true)
        cell.gameWinnerControl.insertSegment(withTitle: game.contestants[1], at: 1, animated: true)
        cell.confidenceTextField.text = String(game.confidence)
        cell.confidenceAverageAllUsersLabel.text = "0"

        return cell

    }

在 UITableViewCell 子类中使用以下内容作为 setter 方法时，我收到Thread 1: EXC_BAD_ACCESS:

set {
    self.game = newValue
}

什么是完成这一切的更好方法？

Answer 1

我决定简单地从我的类中删除 game 变量，并且不使用它。出于某种原因，我认为我需要它，但我意识到我不需要。