如何在没有致命错误的情况下覆盖按钮选择

如何解决如何在没有致命错误的情况下覆盖按钮选择

所以我的目标是能够回到表 vc 并且选择的主题仍然是选定的主题，并在再次加载视图时显示正确的问题。正如你在下面看到的，我有 5 个主题......

这是视图始终加载的方式，我总是使用显示事件问题的 tableview 选择事件主题，这是处理按钮选择的代码：

@IBAction func topicpressed(_ sender: UIButton) {
    eventsTopicButton.isSelected = false
    paymentsTopicButton.isSelected = false
    guestsTopicButton.isSelected = false
    refundsTopicButton.isSelected = false
    profiletopicButton.isSelected = false
    sender.isSelected = true

    switch sender.currentTitle {
    case "Events":
        rowsTodisplay = eventQuestions
        questionTableView.reloadData()
        eventsTopicButton.backgroundColor = #colorLiteral(red: 0.3084011078,green: 0.5618229508,blue: 0,alpha: 1)
        profiletopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,green: 0.6000000238,blue: 0.6000000238,alpha: 1)
        paymentsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
        refundsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
        guestsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
    case "Payments":
        rowsTodisplay = paymentQuestions
        questionTableView.reloadData()
        eventsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
        paymentsTopicButton.backgroundColor = #colorLiteral(red: 0.3084011078,alpha: 1)
    case "Guests":
        rowsTodisplay = guestQuestions
        questionTableView.reloadData()
        eventsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
        guestsTopicButton.backgroundColor = #colorLiteral(red: 0.3084011078,alpha: 1)
    case "refunds":
        rowsTodisplay = refundQuestions
        questionTableView.reloadData()
        eventsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
        refundsTopicButton.backgroundColor = #colorLiteral(red: 0.3084011078,alpha: 1)
    case "Profile":
        rowsTodisplay = profileQuestions
        questionTableView.reloadData()
        profiletopicButton.backgroundColor = #colorLiteral(red: 0.3084011078,alpha: 1)
        eventsTopicButton.backgroundColor = #colorLiteral(red: 0.6000000238,alpha: 1)
    
  
    default:
        break
    }
    
}

现在我遇到的问题是，当单击一个单元格并从与 Events 不同的选定主题转到 vc 时，当退出 vc 并返回到常见问题解答主页时，事件按钮是默认情况下选中，我想覆盖它。所以我尝试在被选中单元格vc中运行此代码块，我得到一个线程错误，说值是nil。

override func prepare(for segue: UIStoryboardSegue,sender: Any?) {
    let vc = segue.destination as! FrequentlyAskedQuestionsViewController
    switch segue.identifier {
    case Constants.GuestQuestions.fromGuestQ1AnswerBackToFAQ:
        vc.rowsTodisplay = vc.guestQuestions
        vc.guestsTopicButton.backgroundColor = #colorLiteral(red: 0.3084011078,alpha: 1)
        vc.eventsTopicButton.backgroundColor = #colorLiteral(red: 0.6666666865,green: 0.6666666865,blue: 0.6666666865,alpha: 1)
 //        case Constants.GuestQuestions.fromGuestQ2AnswerBackToFAQ:
 //            vc.guestsTopicButton.isSelected = true
//            vc.eventsTopicButton.isSelected = false
    default:
        break
    }
}

vc.rowsTodisplay.. 行完全正常，但如果显示了正确的行，但根本没有选择应该选择的按钮，则 UI 会产生误导。在我尝试使用它们之后，我也注释掉了底部的 2 行，但也出现了线程错误，说该值为零。我无法理解价值如何为零，如果有人能帮助解释这一点并提供解决方案，那就太好了。谢谢