Question

我看过相关文章，但我不明白为什么我的ViewController中没有调用它。

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

    print("prepare in Start got triggered")

    if segue.destination is RegistrationViewController {

        let newVC = sender as? RegistrationViewController
        newVC?.testString = "Mission accomplished, passed this data"
    }

}

我通过按下按钮来调用

performSegue(withIdentifier: "RegistrationFromStart", sender: self)

testString是RegistrationViewController中的一个属性 segue发生了，没问题，但是属性从不改变，prepare也不会触发打印命令。

我在RegistrationViewController的viewDidLoad中打印testString

  print("RegistrationViewController testString \(testString)")

谢谢您的帮助。

Answer 1

简单地

let newVC = sender as? RegistrationViewController
newVC?.testString = "Mission accomplished, passed this data"

无效

由于sender无法转换为RegistrationViewController

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

  if let des = segue.destination as? RegistrationViewController {
      des.testString = "Mission accomplished, passed this data"
  }

}

您的segue连接源应该是VC本身，而不是来自任何动作，并且应位于IBAction内，例如set

performSegue(withIdentifier: "RegistrationFromStart", sender:nil)

Answer 2

谢谢。感谢您指出这一点。

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    print("prepare in Start got triggered")

    if segue.destination is RegistrationViewController {

        let newVC = segue.destination as? RegistrationViewController
        newVC?.testString = "Mission accomplished, passed this data"
    }

}

也就是说，它从不触发print语句，但是它确实传递了数据，这就是重点。您的意思是，我是从IBAction调用它的

 @IBAction func startKiosk(_ sender: Any) {
    clickSound?.play()
    performSegue(withIdentifier: "RegistrationFromStart", sender: self)
 }

准备（用于segue ：）不被调用

2 个答案: