未调用协议函数

Question

请协助。我想要达到的目标是当我点击特定的 collectionViewCell 时，ReportDetailsMapController 被推送并且我的报告 [indexPath.item] 从 MainController 发送到 ReportDetailsMapController.

协议：

 protocol MainControllerDelegate: class {
     func sendReport(data: ReportModel)
 }

第一个 VC:

 class MainController: UIViewController, UICollectionViewDelegate,UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

    var delegate: MainControllerDelegate?


    override func viewDidLoad() {
        super.viewDidLoad()
    }
     
      
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
       let report = reports[indexPath.item]
       //When I print(report.name) here. Everything executes correctly 
     
       self.delegate?.sendReport(data: report)

       self.navigationController?.pushViewController(ReportDetailsMapController(), animated: true)
    }
     

 }

第二VC:

 class ReportDetailsMapController: UIViewController, MainControllerDelegate  {
     
    override func viewDidLoad() {
       super.viewDidLoad()
    
       let mc = MainController()
       mc.delegate = self

     }
      
     func sendReport(data: ReportModel) {

       print(data.name)//This does not execute when ReportDetailsMapController is loaded.
       print("Report sent")

     }


 }

报表模型：

 class ReportModel: NSObject {   
      var name: String?
      var surname: String?
      var cellNumber: String?
 }

Answer 1

该方法未被调用，因为您没有将要推送的视图控制器分配给 delegate 属性。
选择单元格后，您可以按以下顺序执行：初始化视图控制器并将其分配给委托，然后调用委托方法并推送该视图控制器：

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
       let report = reports[indexPath.item]
       //When I print(report.name) here. Everything executes correctly 

       let viewController = ReportDetailsMapController()
       self.delegate = viewController
       self.delegate?.sendReport(data: report)

       self.navigationController?.pushViewController(viewController, animated: true)
    }

但是，我认为更简单、更优雅的方法是简单地在 ReportDetailsMapController 上创建属性并在推送它之前注入它。这里有一个与此相关的类似 question/answer：

未调用协议函数

Protocol Function not being called

delegates

protocols

swift