无法构造“DepartmentDataDelegate”，因为它没有可访问的初始值设定项

Question

我正在使用Protocol和Delegates将api数据保存到委托方法中，并在另一个类中提取它。但在第二堂课时，我宣布了这个属性。它显示一条错误消息。

无法构造“DepartmentDataDelegate”，因为它没有可访问的初始值设定项

A类：添加用于将api数据保存到委托方法的协议。

protocol DepartmentDataDelegate {
    func showDepttData(departments: [String : Any])
}

var delegate: DepartmentDataDelegate?

将api数据存储到协议方法中

do {
                //create json object from data
                if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: [Any]] {
                    //print("POST Method :\(json)")


                    DispatchQueue.main.async {

                        for eachDepartment in json["departments"]!
                        {
                            let eachData = eachDepartment as! [String: Any]

                            self.delegate?.showDepttData(departments: eachData)
                        }
                        self.tableView.reloadData()
                    }

                    // handle json...
                }
            } catch let error {
                print(error.localizedDescription)
}

B类：此类正在获取部门数据并在此处打印。

class ShowEmpVC: UIViewController, DepartmentDataDelegate {

    //Department Data Delegate
    var depttDelegate = DepartmentDataDelegate()

    var depttData = [String : Any]()

    override func viewDidLoad() {
        super.viewDidLoad()

        depttDelegate = self
        print("Departmens  are  :   \(depttData)")
    }
}

Answer 1

在您的协议中没有init()功能。所以你不要打电话给DepartmentDataDelegate()。试试这个：

A类：

protocol DepartmentDataDelegate {
    func showDepttData(departments: [String : Any])
}

static var delegate: DepartmentDataDelegate?

B级：

class ShowEmpVC: UIViewController, DepartmentDataDelegate {

    var depttData = [String : Any]()

    override func viewDidLoad() {
        super.viewDidLoad()

        depttDelegate = self
        print("Departmens  are  :   \(depttData)")
    }

   override func showDepttData(departments: [String : Any]){
      // code
  }
}

我不确定是否需要override键。

Answer 2

协议类

import UIKit

protocol sampleProtocol : class {
    func getValues(valuess:String)
}

class sampleClass {
    /// Shared Instance - So without creating a new Instance i  can make use of its function
    static let shared = sampleClass()
    /// Delegate Object
    var delegate : sampleProtocol?

    /// Sample Func which will send data using protocol
    func sendData(){
        /// Called whnen data is to be Transmitted
        delegate?.getValues(valuess: "output")
    }
}

用法 - 目标类 - 您的案例ShowEmpVC

import UIKit

class sampleVC: UIViewController
{
    override func viewDidLoad() {
        super.viewDidLoad()
        /// Make use of Shared Instance Created so, You need not to Re-allocate a New instance just to make use of Delegate
        sampleClass.shared.delegate = self
    }
}

/// Assign class to Protocol
extension sampleVC : sampleProtocol
{
    /// Protocol stub
    func getValues(valuess: String) {
        /// Get Value
        print(valuess)
    }
}