设置segue函数swift的条件

Question

在一个按钮中，我放置了警报系统和弹出视图。如果文本字段为空，则它将发送警报。如果一切正常，那么它将显示弹出视图。Alart系统和弹出窗口冲突。何时执行或不执行，如何设置segue函数的条件？

函数编写不正确。我能理解。但我在写这篇文章时很困惑。我该如何称呼override函数？

func stateCondition(state: Bool) {
if state {
print("Entered into the state") //entering into the func
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "info"{
_ = segue.destination as! InfoViewController
}
if segue.identifier == "popUp" {
let vc = segue.destination as! PopUpViewController
vc.age = Double(ageTextField.text!)!
vc.gender = genderTextField.text!
vc.bmi = Double(bmiLabel.text!)!
print("Entered into the segue") //is not entering into this func
}
}
}
}

Answer 1

尝试阅读代码和注释。首先方法func prepare(for segue: UIStoryboardSegue, sender: Any?)不能在另一个方法中。不知怎么的，你设法把它挤到了func stateCondition(state: Bool)里第二次您不会在任何地方呼叫performSegue(withIdentifier: identifier, sender: self)。您可能应该：(查看代码，希望它能有所帮助。我记得我的第一节课，我花了一些时间才明白发生了什么

class ViewController: UIViewController {
@IBOutlet private var ageTextField: UITextField!
@IBOutlet private var genderTextField: UITextField!
@IBOutlet private var bmiLabel: UILabel!
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// 3
// This method gets called and there you do your stuff with respective VCs
if segue.identifier == "info", let infoViewController = segue.destination as? InfoViewController {
// 3.1
// If the identifer is set to INFO then you go to the InfoViewController and assigne message
infoViewController.message = "Some fields are empty"
} else if segue.identifier == "popUp", let popUpViewController = segue.destination as? PopUpViewController {
// 3.2
// If the identifer is set to POPUP then you go to PopUpViewController and assign age, gender and bmi
popUpViewController.age = "33"
popUpViewController.gender = "male"
popUpViewController.bmi = "20"
} else {
print("Identifer is none of the above")
}
}
@IBAction private func buttonTapped(_ sender: Any) {
// 1.
// First you need to figure out where you want to take the user
// You do that in the method getSegueIdentifier() where you get the identifier
let identifier = getSegueIdentifier()
// 2.
// Then you performSegue with that identifer
performSegue(withIdentifier: identifier, sender: self)
}
private func getSegueIdentifier() -> String {
if ageTextField.text?.isEmpty == true && genderTextField.text?.isEmpty == true && bmiLabel.text?.isEmpty == true {
return "info"
} else {
return "popUp"
}
}
}
class InfoViewController: UIViewController {
var message = ""
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
showAlert()
}
func showAlert() {
// show alert with message
print(message)
}
}
class PopUpViewController: UIViewController {
var age = ""
var gender = ""
var bmi = ""
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
showPopUp()
}
func showPopUp() {
// show popUp with age gender and bmi
print(age, gender, bmi)
}
}

Answer 2

有一个普遍的误解：您不能调用prepare(for segue——而且语法无论如何都是错误的——函数是在执行segue之前由框架调用的。

你的意思可能是

func stateCondition(state: Bool) {
if state {
print("Entered into the state") //entering into the func
performSegue(withIdentifier: "info", sender: nil)
} else {
performSegue(withIdentifier: "popUp", sender: nil)
}
}
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "popUp" {
let vc = segue.destination as! PopUpViewController
vc.age = Double(ageTextField.text!)!
vc.gender = genderTextField.text!
vc.bmi = Double(bmiLabel.text!)!
print("Entered into the segue") //is not entering into this func
}
}