How can I pass dictionary from one view controller class to another?SWIFT - ios

Question

I am trying to make a list of users and their passwords in one view controller, save that information in a dictionary, and send that dictionary to another view controller which asks the user to input their username/password combination to authorize the log in. (the key is the username and the value is the password). Is there a way I can send the dictionary from SecondVC to the FirstVC?
First View Controller
class ViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var Username: UITextField!
#IBOutlet weak var Verification: UILabel!
#IBOutlet weak var Password: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
Username.delegate = self
Password.delegate = self
}
var usersDict = [String : String]()
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let des = segue.destination as? AccountViewController {
des.usersDict = usersDict
}
}
#IBAction func Authorization(_ sender: Any) {
for ( key , value ) in usersDict{
let v = key.count
var start = 0
if start <= v{
if Username.text == key{
if Password.text == value{
Verification.text = "Looks Good"
}
}
else{
start += 1
}
}
else{
Verification.text = "Yikes"
}
}
}
}
Second View Controller
class AccountViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var CreateUsername: UITextField!
#IBOutlet weak var CreatePassword: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
CreateUsername.delegate = self
CreatePassword.delegate = self
// Do any additional setup after loading the view.
}
var usersDict = [ String : String ]()
#IBAction func MakeANewAccount(_ sender: Any) {
usersDict[CreateUsername.text!] = CreatePassword.text!
}
}
I have made there dictionary, but it will only send in the beginning and won't update after creating the original account. (dictionary it is sending is empty)

Answer 1

With a segue add this method inside ViewController
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let des = segue.destination as? AccountViewController {
des.usersDict = yourDicHere
}
}

Answer 2

Here's a general pattern for making a controller work with data from some object it creates, in this case a second controller.
Try applying it to your situation and let me know if you run into problems.
protocol Processor {
func process(_ dict: [String : String])
}
class FirstController: UIViewController, Processor {
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let controller = segue.destination as? SecondController {
controller.delegate = self
} else {
print("Unexpected view controller \(segue.destination)")
}
}
func process(_ dict: [String : String]) {
}
}
class SecondController: UIViewController {
var delegate: Processor?
func someWork() {
if let processor = delegate {
processor.process(["Name" : "Pwd"])
} else {
print("Delegate not assigned")
}
}
}