ios - 协议(protocol)代理无法按预期方式返回nil swift

我有一个以编程方式创建的searchBar。我只是想要这样，一旦单击searchBar内部的背面图像，就会调用ViewController内部的函数。我已经尝试了所有我知道的东西，但是我似乎无法弄清楚delegate为什么总是返回nil。

ViewControllerClass

    class ProductByCategoryView: UIViewController {
    // Content container
    var category: ProductCategory!
    var searchHeaderBrief: SearchHeaderBrief! = SearchHeaderBrief()

      lazy var container: UIStackView = {
          let contentView = UIStackView(frame: .zero)
          contentView.axis = .vertical
          contentView.spacing = 10
          contentView.willSetConstraints()
          return contentView
      }()

      var searchHeader: SearchHeaderBrief! // Header section

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.white
         self.setupInterface()

    }
        // MARK: SEARCH HEADER
        private func setupSearch() {
            self.searchHeaderBrief.backDelegate = self
            self.searchHeader = SearchHeaderBrief(frame: .zero)
            self.searchHeader.willSetConstraints()

            self.container.addArrangedSubview(self.searchHeader)
            let constraints = [
                self.searchHeader.topAnchor.constraint(equalTo: self.container.topAnchor),
                self.searchHeader.heightAnchor.constraint(equalToConstant:130),
                self.searchHeader.widthAnchor.constraint(equalTo: self.view.widthAnchor),
            ]
            NSLayoutConstraint.activate(constraints)

            DispatchQueue.main.async {
                self.searchHeader.backgroundColor = UIColor(patternImage: UIImage(named: "header_background")!.resize(to: CGSize(width: self.searchHeader.bounds.width, height: self.searchHeader.bounds.height)))
                self.searchHeader.setGradientBackground(gradientTop: UIColor.constants.darkBlue.withAlphaComponent(0.9).cgColor, gradientBottom: UIColor.constants.darkBlue.cgColor, opacity: 0.9)
                self.searchHeader.applyConstraints()
            }
        }
    private func setupInterface() {
        self.embedInScrollView(content: self.container)
        self.setupSearch() // Search
        DispatchQueue.main.async {
            self.container.setBackground(color: UIColor.constants.lightGray)
        }
    }
}
extension ProductByCategoryView: BackDelegate {
       func goBack() {
           self.back()
       }
   }

CustomViewClass

 protocol BackDelegate: AnyObject {
      func goBack()
  }
class SearchHeaderBrief: UIView {
    lazy var searchBox: UITextField! = {
        return self.searchField()
    }()
//   var filterDelegate: SearchHeaderDelegateBrief?
    var backDelegate: BackDelegate?
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.setup()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        self.setup()
    }

    func setup() {
        self.addSubview(self.searchBox)
        self.setNeedsDisplay()
    }

    func searchField() -> UITextField {
        let search = UITextField(frame: .zero)
        search.layer.backgroundColor = UIColor.white.cgColor

        // Search Icon
        let searchIconView = UIView(frame: CGRect(x: 0, y: 0, width: 32, height: 40))
        let searchIcon = UIImageView(frame: CGRect(x: 7.5, y: 11.5, width: 17, height: 17))
        searchIcon.contentMode = .scaleAspectFill
        searchIcon.image = UIImage(named: "ic_back")!
        let singleTap = UITapGestureRecognizer(target: self, action: #selector(tapDetected))
        searchIcon.isUserInteractionEnabled = true
        searchIcon.addGestureRecognizer(singleTap)
        searchIconView.addSubview(searchIcon)
        search.leftView = searchIconView
        search.leftViewMode = .always

        // Filter icon
        let filterIconView = UIView(frame: CGRect(x: 0 , y: 0, width: 40, height: 40))
        filterIconView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.showSearchFilters)))
        filterIconView.isUserInteractionEnabled = true

        let filterIcon = UIImageView(frame: CGRect(x: 6.5 , y: 9.5, width: 27, height: 21))
        filterIcon.image = UIImage(named: "ic_filter")!
        filterIcon.contentMode = .scaleAspectFit
        filterIconView.addSubview(filterIcon)

        search.rightView = filterIconView
        search.rightViewMode = .always

        search.layer.cornerRadius = 3
        search.translatesAutoresizingMaskIntoConstraints = false
        search.clipsToBounds = true
        search.addShadow()
        return search
    }

    func applyConstraints() {
        NSLayoutConstraint.activate([
            self.searchBox.heightAnchor.constraint(equalToConstant: 43),
            self.searchBox.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 15),
            self.searchBox.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -15),
            self.searchBox.topAnchor.constraint(equalTo: self.topAnchor, constant: 40),
        ])
        self.layoutIfNeeded()
    }

    @objc func showSearchFilters() {
      //  self.filterDelegate?.filter()
    }
    //Action
    @objc func tapDetected() {
        self.backDelegate?.goBack()
    }
}

最佳答案

更新你的方法

// MARK: SEARCH HEADER
        private func setupSearch() {
            self.searchHeaderBrief.backDelegate = self
            self.searchHeader = SearchHeaderBrief(frame: .zero)
            self.searchHeader.willSetConstraints()
            self.searchHeader.backDelegate = self
            self.container.addArrangedSubview(self.searchHeader)
            let constraints = [
                self.searchHeader.topAnchor.constraint(equalTo: self.container.topAnchor),
                self.searchHeader.heightAnchor.constraint(equalToConstant:130),
                self.searchHeader.widthAnchor.constraint(equalTo: self.view.widthAnchor),
            ]
            NSLayoutConstraint.activate(constraints)

            DispatchQueue.main.async {
                self.searchHeader.backgroundColor = UIColor(patternImage: UIImage(named: "header_background")!.resize(to: CGSize(width: self.searchHeader.bounds.width, height: self.searchHeader.bounds.height)))
                self.searchHeader.setGradientBackground(gradientTop: UIColor.constants.darkBlue.withAlphaComponent(0.9).cgColor, gradientBottom: UIColor.constants.darkBlue.cgColor, opacity: 0.9)
                self.searchHeader.applyConstraints()
            }
        }

关于ios - 协议(protocol)代理无法按预期方式返回nil swift ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/61675216/