简单创建一个Manager类

示例代码，创建一个界面，界面含有一个监听，成功之后传给调用Manager的类

import UIKit

public class Manager: NSObject {
    public static let getInstance = Manager()
    
    func start(self:UIViewController,callBack: ((_ msg:String) -> Void)? = nil) {
        let viewController = UIStoryboard.init(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewController") as! ViewController
        viewController.Start(callBack: callBack)
//        viewController.modalPresentationStyle = .fullScreen
        self.present(viewController, animated: true, completion:nil)
    }
}

ViewController监听调用

public func start(callBack: ((_ msg:String) -> Void)? = nil) {
        handle = Auth.auth().addStateDidChangeListener { auth, user in
            if user == nil{
                // go to main screen if there is a user logged in
                print("登出状态")
                self.loginContext.text = "User is signed out !"
            }else{
                //go to login screen
                self.currentUser = user
                print("登录状态")
                self.loginContext.text = "UserId:\(user?.uid ?? "")\nProviderId:\(user?.providerID ?? "")\nDisplayName:\(user?.displayName ?? "")\nPhoneNum:\(user?.phoneNumber ?? "")\nEmail:\(user?.email ?? "")\nIsEmailVerified:\(user!.isEmailVerified)\nPhotoUrl:\(user?.photoURL?.absoluteString ?? "")"
            }
            guard let _callBack = callBack else { return }
            _callBack(user?.providerID ?? "")
        }
     }

调用

        Manager.getInstance.startLogin(self: self) { msg in
            print("数据传递成功------>"+msg)
        }