ios - 我正在尝试 Segue 并传递一个字符串，但出现错误

Question

当我尝试执行到另一个 View Controller 的segue 时，出现此错误。我不知道为什么会收到此错误？

线程 1:EXC_BAD_ACCESS

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "NormalPushupSegue" {
            let normalVC = segue.destination as! PopupViewController
            normalVC.formType = "Normal"
            performSegue(withIdentifier: "NormalPushupSegue", sender: self)
        }
        if segue.identifier == "DiamondPushupSegue" {
            let diamondVC = segue.destination as! PopupViewController
            diamondVC.formType = "Diamond"
            performSegue(withIdentifier: "DiamondPushupSegue", sender: self)
        }
        if segue.identifier == "WidePushupSegue" {
            let wideVC = segue.destination as! PopupViewController
            wideVC.formType = "Wide"
            performSegue(withIdentifier: "WidePushupSegue", sender: self)
        }
        if segue.identifier == "DeclinePushupSegue" {
            let declineVC = segue.destination as! PopupViewController
            declineVC.formType = "Decline"
            performSegue(withIdentifier: "DeclinePushupSegue", sender: self)
        }
    }

Answer 1

首先，最好安全地解开 View Controller 。就像这样:

if let myViewController = segue.destination as? MyViewController { 
    // Set up the VC, add some values and options
}

第二 - 您不需要调用 performSegue ，perform for segue 已经在调用您的 View Controller 。只需删除 performSegue

第三 - 您可以使其变得更容易并应用这样的逻辑:

enum AppSegueName: String {
case Normal = "NormalPushupSegue"
case Diamond = "DiamondPushupSegue"
case Wide = "WidePushupSegue"
case Decline = "DeclinePushupSegue"
}

extension AppSegueName: CaseIterable {}

并在准备函数中使用 switch\case 语句并将 AppSegueName 原始值与 segue.identifier 进行比较

像这样:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    AppSegueName.allCases.forEach {
        if $0.rawValue == segue.identifier {

            if let myViewController = segue.destination as? MyViewController { 
            myViewController.formType = $0 // formType is of type AppSegueName
            }
        }
    }
}