Инициализатор недоступен из-за «внутреннего» уровня защиты

У меня есть протоколы

LoginStrategy

public protocol LoginStrategy {
    func login(_ viewController: UIViewController)
    func getUserInfo(withCompletionHandler completionHandler: @escaping (_ userInfo: [String: Any]?) -> ())
    func createLoginButton(_ frame: CGRect, withCompletionHandler completionHandler: @escaping (_ loginButton: UIView) -> ())
    func getUserId() -> String
}

и два класса:

LoginProvider

public class LoginProvider {

    public let strategy: LoginStrategy

    public func login(_ viewController: UIViewController) {
        return self.strategy.login(viewController)
    }

    public func getUserInfo(withCompletionHandler completionHandler: @escaping (_ userInfo: [String: Any]?) -> ()) {
        return self.strategy.getUserInfo(withCompletionHandler: completionHandler)
    }

    public func createLoginButton(_ frame: CGRect, withCompletionHandler completionHandler: @escaping (_ loginButton: UIView) -> ()) {
        return self.strategy.createLoginButton(frame, withCompletionHandler: completionHandler)
    }

    public func getUserId() -> String {
        return self.strategy.getUserId()
    }

    public init(strategy: LoginStrategy) {
        self.strategy = strategy
    }

}

FacebookLoginStrategy

import Foundation
import FacebookCore
import FacebookLogin

public class FacebookLoginStrategy: LoginStrategy {

    public var grantedPermissions: Set<Permission>? = nil

    public var declinedPermissions: Set<Permission>? = nil

    public var userId: String = ""

    public func login(_ viewController: UIViewController) {
        let loginManager = LoginManager()
        let permissions: [ReadPermission] = [.publicProfile, .userFriends, .email]
        loginManager.logIn(permissions, viewController: viewController) { loginResult in
            switch loginResult {
            case .failed(let error):
                print(error)
            case .cancelled:
                print("User cancelled login.")
            case .success(let grantedPermissions, let declinedPermissions, let accessToken):
                self.userId = accessToken.userId ?? ""
                self.grantedPermissions = grantedPermissions
                self.declinedPermissions = declinedPermissions
                print("Logged in!")
            }
        }
    }

    public func getUserId() -> String {
        return userId
    }

    public func getUserInfo(withCompletionHandler completionHandler: @escaping (_ userInfo: [String: Any]?) -> ()) {
        let request = GraphRequest(graphPath: "me", parameters: ["fields":"email, name"], accessToken: AccessToken.current, httpMethod: .GET, apiVersion: FacebookCore.GraphAPIVersion.defaultVersion)
        request.start { (response, result) in
            switch result {
            case .success(let value):
                print(value.dictionaryValue)
                completionHandler(value.dictionaryValue)
            case .failed(let error):
                print(error)
            }
        }
    }

    public func createLoginButton(_ frame: CGRect, withCompletionHandler completionHandler: @escaping (_ loginButton: UIView) -> ()) {
        let permissions: [ReadPermission] = [.publicProfile, .userFriends, .email]
        let loginButton = LoginButton(readPermissions: permissions)
        loginButton.frame = frame
        completionHandler(loginButton)
    }
}

В моем ViewController:

Когда я использую:

let facebookLoginProvider = LoginProvider(strategy: FacebookLoginStrategy())

Он говорит:

FacebookLoginStrategy недоступен из-за «внутреннего» уровня защиты