Myujth

I am trying to implement a login screen that would put data into a view controller, the login view controller is called by overriding tabBarController didSelect method, just as follows:

Note that there is not any segue between the TabBarController and the ThirdViewController, because I override tabBarController as follows:

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UITabBarControllerDelegate 

// This delegate open the modal view after open the desired view.
 func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) 
 if viewController is MyThirdViewController 
 if let loginPopupVC = tabBarController.storyboard?.instantiateViewController(withIdentifier: "LoginViewController") 
 tabBarController.present(loginPopupVC, animated: true)
 
 
 

Now, in my LoginViewController I parse a JSON in a struct (LoginResponse) with the data that is supposed to fill the ThirdViewController (name, surnames, sex, birth, and so on). I already do this with this snippet inside LoginViewController:

struct LoginResponse : Decodable 
 var name: String
 var surname: String
 var sex: String
 var birth: String


class LoginViewController: UIViewController, UITextFieldDelegate, XMLParserDelegate 

@IBAction func cancelLogin(_ sender: UIButton) 
 //LoginViewController will close and ThirdViewController will open
 dismiss(animated: true, completion: nil)
 

@IBAction func makeLogin(_ sender: UIButton) 
 //LoginViewController brings data, closing itself and opening ThirdViewController
 self.updateUI()
 self.dismiss(animated: true, completion: nil)
 

func updateUI() 
 do 
 let jsonDecoder = JSONDecoder()
 let myjson = ""name": "MyName", "surname": "MySurname", "sex": "Male", "birth": "1980-05-15""
 let loginResult = try jsonDecoder.decode(LoginResponse.self, from: Data(myjson.utf8))
 
 catch let jsonErr
 print(jsonErr)
 

 

Now, I want to pass that data (inside loginResult) to ThirdViewController.

I guess that I cannot invoke ThirdViewController from LoginViewController, because TabBarController already did it, and that it is necessary if I choose pass data using Delegate method or NotificationCenter method.

I wanna know which of the passing-data options between ViewControllers would work better in this case, because usually that methods are explained in examples with two view controllers connected by a segue, but in my case, the flow of the screens is unusual. Thanks.

You can try something like this:

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UITabBarControllerDelegate 

 // This delegate open the modal view after open the desired view.
 func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) 
 if viewController is MyThirdViewController 
 if let loginPopupVC = tabBarController.storyboard?.instantiateViewController(withIdentifier: "LoginViewController") 
 loginPopupVC.delegate = tabBarController
 tabBarController.present(loginPopupVC, animated: true)
 
 
 

For loginPopupVC:

struct LoginResponse : Decodable 
 var name: String
 var surname: String
 var sex: String
 var birth: String


class LoginViewController: UIViewController, UITextFieldDelegate, XMLParserDelegate 

 var delegate: loginDelegate?

 @IBAction func cancelLogin(_ sender: UIButton) 
 //LoginViewController will close and ThirdViewController will open
 dismiss(animated: true, completion: nil)
 

 @IBAction func makeLogin(_ sender: UIButton) 
 //LoginViewController brings data, closing itself and opening ThirdViewController
 self.updateUI()
 self.dismiss(animated: true, completion: nil)
 

 func updateUI() 
 do 
 let jsonDecoder = JSONDecoder()
 let myjson = ""name": "MyName", "surname": "MySurname", "sex": "Male", "birth": "1980-05-15""
 let loginResult = try jsonDecoder.decode(LoginResponse.self, from: Data(myjson.utf8))
 // Pass data using delegate
 delegate?.handleLogin(with: loginResult)

 
 catch let jsonErr
 print(jsonErr)
 

 

And then for your tabBarController class:

protocol loginDelegate: class 
 func handleLogin(with object: LoginResponse)


class myTabBarController: UITabBarController, loginDelegate 

 // regular tabBarController lifecycle methods

 func handleLogin(with object: LoginResponse) 
 // do work with data
 

Right. I would suggest declaring a variable in loginPopupVC to contain a reference to ThirdViewController, so in tabBar:didSelect after instantiating the loginVC you pass it a reference to ThirdVC, but before presenting the login. In Login, said variable is class level, so you can access it from the updateUI func. Now, declare a method or variable in ThirdView to contain the json and just pass it.