解雇后是否取消ViewController的首字母缩写

Question

我的应用程序中有两个viewController，第一个viewController的代码如下所示：

import UIKit
class firstViewController: UIViewController {
// The below two variables will be passed from the firstViewController to the secondViewController then back again from the secondViewController to the firstViewController:
var selectedRowValue: Int = 0
var selectedSectionValue: Int = 0
let main = UIStoryboard(name: "Main", bundle: nil)
lazy var secondViewController = main.instantiateViewController(withIdentifier: "secondViewController")
override func viewDidLoad() {
super.viewDidLoad()
}
// The below function will be triggered when the user tap on a specific tableView cell detailClosure icon. This is when the needed data get sent from this viewController to the secondViewController:
func tableView(_ tableView: UITableView, accessoryButtonTappedForRowWith indexPath: IndexPath) {
let secondViewControllerProperties = secondViewController as! secondViewController
secondViewControllerProperties.receivedSelectedSectionValueFromFirstVc = indexPath.section
secondViewControllerProperties.receivedSelectedRowValueFromFirstVc = indexPath.row
// The below is the relevant content of a UILabel inside the tapped tableView cell by the user that get send to the secondViewController for it to be displayed as its NavigationBar title:
secondViewControllerProperties.selectedUniversalBeamSectionDesignation = arrayWithAllDataRelatedToUbsSections.filter({ $0.sectionSerialNumber == "(arrayWithAllSectionsSerialNumbers[indexPath.section])" }).map({ $0.fullSectionDesignation })[indexPath.row]
self.present(secondViewControllerProperties, animated: true, completion: nil)
}
}
// The below extension inside the firstViewController is used to pass data back from the secondViewController to the firstViewController:
extension firstViewController: ProtocolToPassDataBackwardsFromSecondVcToFirstVc {
func dataToBePassedUsingProtocol(passedSelectedTableSectionNumberFromPreviousVc: Int, passedSelectedTableRowNumberFromPreviousVc: Int) {
self.selectedRowValue = passedSelectedTableRowNumberFromPreviousVc
self. selectedSectionValue = passedSelectedTableSectionNumberFromPreviousVc
}
}

下面是第二个视图控制器内部的代码：

import UIKit
class secondViewController: UIViewController {
weak var delegate: ProtocolToPassDataBackwardsFromSecondVcToFirstVc?
// The below variables get their values when the data get passed from the firstViewController to the secondViewController:
var receivedSelectedRowValueFromFirstVc: Int = 0
var receivedSelectedSectionValueFromFirstVc: Int = 0
var selectedUniversalBeamSectionDesignation: String = ""
// Inside the below navigationBar declaration, its labelTitleText will depend on the tapped tableViewCell by the user inside the firstViewController:
lazy var navigationBar = CustomUINavigationBar(navBarLeftButtonTarget: self, navBarLeftButtonSelector: #selector(navigationBarLeftButtonPressed(sender:)), labelTitleText: "UB (selectedUniversalBeamSectionDesignation)", navBarDelegate: self)
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(navigationBar)
}
// The below gets triggered when the user hit the back button inside the navigationBar of the secondViewController. This is where using the Protocol data get passed back to the firstViewController: 
extension secondViewController: UINavigationBarDelegate {
@objc func navigationBarLeftButtonPressed(sender : UIButton) {
if delegate != nil {
delegate?.dataToBePassedUsingProtocol(passedSelectedTableSectionNumberFromPreviousVc: self.selectedTableSectionNumberFromPreviousViewController, passedSelectedTableRowNumberFromPreviousVc: self.selectedTableRowNumberFromPreviousViewController)
}
dismiss(animated: true) {}
}
}

然而，我注意到的是，每当用户点击secondViewController导航栏内的后退按钮时，secondViewController就会被关闭。secondViewController不会被取消初始化，因此，每当我在firstViewController中的tableView中按下不同的单元格时，secondViewController中显示的导航栏标题仍然与我第一次按下时显示的标题相同。由于secondViewController没有被取消初始化，因此，我看到的值与第一次初始化时相同。

我的问题是，当secondViewController被驳回时，如何取消初始化它，以便每次我点击firstViewController内的tableView内的不同单元格时，都会初始化一个新的secondViewController？

Answer 1

您的代码生成secondViewController一次并重用它(它是一个属性(。

lazy var secondViewController = main.instantiateViewController(withIdentifier: "secondViewController")

这意味着它将一直存在，直到第一个视图控制器被破坏，当然，它将被重用
相反，您应该根据需要创建它。

func tableView(_ tableView: UITableView, accessoryButtonTappedForRowWith indexPath: IndexPath) {
// Create the second view controller
let secondViewController = main.instantiateViewController(withIdentifier: "secondViewController")
let secondViewControllerProperties = secondViewController as! secondViewController
secondViewControllerProperties.receivedSelectedSectionValueFromFirstVc = indexPath.section
secondViewControllerProperties.receivedSelectedRowValueFromFirstVc = indexPath.row
// The below is the relevant content of a UILabel inside the tapped tableView cell by the user that get send to the secondViewController for it to be displayed as its NavigationBar title:
secondViewControllerProperties.selectedUniversalBeamSectionDesignation = arrayWithAllDataRelatedToUbsSections.filter({ $0.sectionSerialNumber == "(arrayWithAllSectionsSerialNumbers[indexPath.section])" }).map({ $0.fullSectionDesignation })[indexPath.row]
self.present(secondViewControllerProperties, animated: true, completion: nil)
}
}

删除lazy var当然，不再需要它了
此外，您可以执行以下操作：
let secondViewController = main.instantiateViewController(withIdentifier: "secondViewController") as! SecondViewController，而不是稍后铸造，它会更干净一些。