【发布时间】：2020-07-06 11:31:43
【问题描述】：
我的App中有两个viewController，第一个viewController的代码如下图：
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) {}
}
}
但是，我注意到的是，当用户点击 secondViewController 的导航栏中的后退按钮时，每当 secondViewController 被关闭时。 secondViewController 没有被取消初始化，因此，每当我在 firstViewController 内的 tableView 内按下不同的单元格时，在 secondViewController 内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。
我的问题是如何在 secondViewController 被解除时取消初始化它，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？
【问题讨论】：
-
正如 Moshe 所说，问题在于您的第一个视图控制器对第二个视图控制器保持强引用。这是没有必要的。只需将第二个视图控制器的引用作为
accessoryButtonTappedForRowWith方法中的局部变量即可。此外，您还没有共享CustomUINavigationBar，但请确保它对其委托保持弱引用。 -
一旦你的直接问题抛诸脑后，你可能想重新审视你的班级名称。按照惯例，类名总是以大写字母开头。对于变量、属性等，我们以小写字母开头，但类型总是以大写字母开头。而且，如果您想简化重命名过程（同时在各处更改它们，包括情节提要），您可以右键单击类名并选择“重构”»“重命名...”。
-
谢谢 Rob，我会在考虑您非常感谢的建议后重构我的代码 :)
标签： swift uiviewcontroller protocols deinit