ios - 协议(protocol)/委托(delegate)中 IBOutlet 的困难

Question

我在使用 IBOutlets 时遇到困难。我试图允许用户在 TableView Controller (LoLAddGoalsTableViewController)中输入一个目标(称为 nameOfRewardText)，然后当他们单击“完成”时，让该目标显示在不同 View Controller 中名为“currentGoalTextField”的标签中(LoLGoalViewController)。我一直在尝试使用 Save segue 来实现这一点，但建议使用带有委托(delegate)的协议(protocol)( Updating text in ViewController using Save function )。现在我已经用协议(protocol)和委托(delegate)替换了 Save segue，输入的“nameOfRewardText”文本没有显示在“currentGoalTextField”标签中，我怀疑是因为 IBOutlet 不再正确地绑定(bind)在一起。我附上了下面 Outlet 的代码和屏幕截图，以试图阐明我所在的位置。有谁知道我如何修复 IBOutlet 或者是否需要添加其他内容才能使其正常工作？我删除了将 nameOfRewardText.text 指定为 goal.goalText 的行，所以我认为 nameOfRewardText 没有被指定给 var goal？也许我为此文本使用了太多名称(nameOfRewardText、goalText 和 currentGoalTextField)，这使事情变得复杂？任何帮助将不胜感激，因为我对此很陌生!谢谢大家!

这是结构目标:

import UIKit

struct Goal {
    var goalText: String
    var pointsToCompleteGoal: Int
    var pointsEarnedTowardsGoal: Int
    var repeatGoal: Bool

    init(goalText: String, pointsToCompleteGoal: Int, pointsEarnedTowardsGoal: Int, repeatGoal: Bool = false) { //Made String non-optional. If issue later, can revert.
        self.goalText = goalText
        self.pointsToCompleteGoal = pointsToCompleteGoal
        self.pointsEarnedTowardsGoal = pointsEarnedTowardsGoal
        self.repeatGoal = repeatGoal
    }
}

这是公共(public)协议(protocol):

import Foundation
import UIKit

protocol GoalDelegate: class {
    func passGoal(_ goal: Goal?)
}

这是创建委托(delegate)的位置，正如您所看到的，我将 nameOfRewardText.text 指定为 goal.goalText 的语句现在消失了:

import UIKit

class AddGoalsTableViewController: UITableViewController {

    var goal:Goal?
    var delegate: GoalDelegate?

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// HASHED OUT THE BELOW BECAUSE REPLACING WITH DELEGATE:
//        if segue.identifier == "SaveGoal" {
//            let pointsNeededInt = Int(pointsNeededText.text!)
//            let pointsEarnedInt = Int(goalProgressText.text!)
//            goal = Goal(goalText: nameOfRewardText.text!, pointsToCompleteGoal: pointsNeededInt!, pointsEarnedTowardsGoal: pointsEarnedInt!)
//        }

        if let secondViewController = segue.destination as? LoLGoalViewController{
            delegate = secondViewController
            delegate?.passGoal(goal)
        }
    }

    @IBOutlet var goalTableTitleText : UILabel!
    @IBOutlet weak var goalProgressText: UILabel!
    @IBOutlet weak var nameOfRewardText: UITextField!
    @IBOutlet weak var pointsNeededText: UITextField!
    @IBOutlet weak var repeatSwitch: UISwitch!


override func viewDidLoad() {
    super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

带有 Outlet 的 AddGoalsTableViewController 的屏幕截图:

这里我遵守协议(protocol)，调用函数passGoal:

import UIKit

class LoLGoalViewController: UIViewController, GoalDelegate {

    @IBOutlet weak var currentGoalTextField: UILabel!

    func passGoal(_ goal: Goal?) {
        currentGoalTextField.text = goal?.goalText
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

extension LoLGoalViewController {

    @IBAction func cancelToLoLGoalViewController(_ segue: UIStoryboardSegue) {
    }
}

带有 Outlet 的 LoLGoalViewController 屏幕截图:

Answer 1

您的 LoLGoalViewController View Controller 可能尚未完全加载其所有 socket 。添加我对上一个问题的回答，您可以在 LolGoalViewController 中声明另一个变量:

@IBOutlet weak var currentGoalTextField: UILabel!

var goalText: String = ""

在您的 passGoal 方法中，将字符串设置为 goalText 变量而不是标签的文本:

func passGoal(_ goal: Goal?) {
    goalText = goal?.goalText
}

最后，在 LolGoalViewController 的 viewDidLoad 中，将标签文本设置为 goalText:

override func viewDidLoad() {
    super.viewDidLoad()

    currentGoalTextField.text = goalText
}