ios - swift4:无法将值从当前弹出窗口传递到上一个 View Controller

Question

我正在使用 swift4，我将 View Controller 模态地呈现为弹出窗口，并希望在关闭当前弹出窗口时将数据传回之前的 View Controller ，这是第一个 View Controller :

import UIKit

class SearchResultViewController: UIViewController, UIPopoverPresentationControllerDelegate, PopoupDelegate {

   @IBOutlet var errorLable: UILabel!
   override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if (segue.identifier == "pop") {
        let dest = segue.destination
           if let pop = dest.popoverPresentationController {
               dest.preferredContentSize = CGSize(width: self.view.frame.size.height - 20, height: 500)
               pop.delegate = self
           }
        }
    }

   func adaptivePresentationStyle(for controller: UIPresentationController) -> UIModalPresentationStyle {
       return .none
   }

   func popupValueSelected(value: String) {
        print("value: ", value)
        self.errorLable.text = value
   }
}

这是弹出代码:

import UIKit

class SearchPopoverViewController: UIViewController {

   @IBOutlet var cityLable: UILabel!
   var delegate: PopoupDelegate?

   @IBAction func closeButtonAction(_ sender: Any) {
       self.delegate?.popupValueSelected(value: "hiiiiii from the other side")
       self.dismiss(animated: false, completion: nil)
   }
}

这是PopoupDelegate

import Foundation

protocol PopoupDelegate {
   func popupValueSelected(value: String)
}

当我点击弹出窗口关闭按钮时，弹出窗口应该消失并且 SearchResultViewController 中的 errorLable 应该将它的文本更改为新传递的文本，但是什么都没有发生，只有弹出窗口关闭， 我该怎么办？

Answer 1

你委托(delegate)的函数是错误的，SearchResultViewController 中的函数内部函数:

func popupValueSelected(value: String) {
   func popupValueSelected(value: String) {
       print("value: ", value)
       self.errorLable.text = value
   }
}

应该是:

func popupValueSelected(value: String) {
    print("value: ", value)
    self.errorLable.text = value
}

编辑问题后:

您从未将任何实例分配给委托(delegate)变量。 尝试将委托(delegate)变量名称更改为 popoUpDelegate。

pop.delegate 适用于 UIPopoverPresentationControllerDelegate 而不是您的委托(delegate)。这个函数应该是这样的:

if (segue.identifier == "pop") {
     if let dest = segue.destination.popoverPresentationController as? SearchPopoverViewController {
               dest.preferredContentSize = CGSize(width: self.view.frame.size.height - 20, height: 500)
               dest.popoUpDelegate = self
       }
   }
}

你的 SearchPopoverViewController 看起来像这样:

class SearchPopoverViewController: UIViewController {

   @IBOutlet var cityLable: UILabel!
   var popoUpDelegate: PopoupDelegate?

   @IBAction func closeButtonAction(_ sender: Any) {
       self.popoUpDelegate?.popupValueSelected(value: "hiiiiii from the other side")
       self.dismiss(animated: false, completion: nil)
   }
}