无法构建'DepartmentDataDelegate'，因为它没有可访问的初始化程序

Question

I am using Protocol and Delegates for saving api data into delegate method and in another class, fetching it. But in second class, when i declared this property. It shows an error message.

'DepartmentDataDelegate' cannot be constructed because it has no accessible initializers

Class A : Add protocol for saving api data into the delegate method.

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

var delegate: DepartmentDataDelegate?

Stored api data into protocol method

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)
}

Class B : This class is fetching the department data and print here.

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

In your protocol not have a init() func. So you not call DepartmentDataDelegate() . Try this:

Class A:

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

static var delegate: DepartmentDataDelegate?

Class B:

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
  }
}

I not sure if needs override key.

Answer 2

Protocol class

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")
    }
}

Usage -- Destination Class -- Your case 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)
    }
}