Swift pushViewController导致应用程序崩溃

Question

我是这里快速开发的新手，试图更改iOS 13的演示样式以使用push样式。原始资源使用情节提要为视图控制器设置演示样式，但是其中一部分使用[

覆盖

    override func prepare(for segue: UIStoryboardSegue, sender: Any?)

我设法通过pushViewController进行了转换，但是应用立即崩溃了，请问这是什么问题？这是全功能

        override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let selectedIndex:Int? = menuTableView.indexPathForSelectedRow?.row


    if (selectedIndex! == 0 || selectedIndex! == 1){
        let submitViewController: SubmitViewController = segue.destination as! SubmitViewController

        if (selectedIndex! == 0){
            submitViewController.currency = Constant.CURRENCY_MYR
        }else{
            submitViewController.currency = Constant.CURRENCY_SGD
        }
    }else if (selectedIndex! == MENU_ACCOUNT_STATISTIC_INDEX){

        let target: SearchResultViewController = segue.destination as! SearchResultViewController


        target.toolbarOption = SearchResultViewToolBarOption.TOOLBAR_SMS
        target.resultContent = self.resultContent

        self.navigationController!.pushViewController(target, animated: true)



    }

这是我得到的错误日志

    2020-04-04 14:50:24.227072+0800 vboss[38120:1974490] *** Terminating app due to uncaught          exception 'NSInvalidArgumentException', reason: 'Application tried to present modally an active controller <vboss.MenuViewController: 0x7fd906087e00>.'

Answer 1

var selectedIndex : Int = -1

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    self.selectedIndex = indexPath.row
    if (selectedIndex == 0 || selectedIndex == 1){
        self.performSegue(withIdentifier: "submitViewController", sender: nil)
    }else if (selectedIndex == MENU_ACCOUNT_STATISTIC_INDEX){
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let target = storyboard.instantiateViewController(withIdentifier: "searchResultViewController") as! SearchResultViewController
        target.resultContent = self.resultContent
        navigationController?.pushViewController(target, animated: true)
    }
}


override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    if let submitViewController: ViewController = segue.destination as! SubmitViewController{
        if (selectedIndex == 0){
            submitViewController.currency = Constant.CURRENCY_MYR
        }else{
            submitViewController.currency = Constant.CURRENCY_SGD
        }
    }
}

Answer 2