Delegate is still nil

Question

I am passing user data from a view controller called CreateNewAccount to another view controller called ThanksForJoining. For some reason my delegate is nil. I am using a segue in order to set my vc.delegate to self (= self) and the segue identifier "thanksForJoining" refers to the segue that connects CreateNewAccount to ThanksForJoining on the storyboard. Somehow though, the delegate remains nil.

CreateNewAccount:

import UIKit

protocol UserInfoDelegate {
   func sendUserInfo(firstName: String, lastName: String, username: String, password: String)
}

class CreateNewAccount: UIViewController{
    @IBOutlet weak var FNInput: UITextField!
    @IBOutlet weak var LNInput: UITextField!
    @IBOutlet weak var usernameInput: UITextField!
    @IBOutlet weak var passwordInput: UITextField!

    var infoDelegate: UserInfoDelegate?

    @IBAction func sendInfo(_ sender: Any) {
        if(infoDelegate != nil){
            if(FNInput.text != nil && LNInput.text != nil && usernameInput.text != nil && passwordInput.text != nil){
                let firstName = FNInput.text
                let lastName = LNInput.text
                let username = usernameInput.text
                let password = passwordInput.text

                infoDelegate?.sendUserInfo(firstName: firstName!, lastName: lastName!, username: username!, password: password!)
            }
        }
    }
}

ThanksforJoining:

import UIKit

class ThanksForJoining: UIViewController, UserInfoDelegate {
    @IBOutlet weak var fName: UILabel!

    func sendUserInfo(firstName: String, lastName: String, username: String, password: String) {
        print(firstName)
        fName.text = firstName
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if (segue.identifier == "thanksForJoining") {
            let createNewAccount: CreateNewAccount = segue.destination as! CreateNewAccount
            createNewAccount.infoDelegate = self
        }
    }
}

Answer 1

First of all, you need to confirm that:

• You connected CreateNewAccount to ThanksForJoining via a segue.

• The segue's Identifier is set to thanksForJoining correctly (Be careful about the letter cases.)

If any of the two is not true, you have lost a little time and I have lost my time to prepare for a big typhoon. Update your question to clarify what's happening and wait for someone to help you...

---

Assuming two things above, prepare(for:sender:) is called on the source view controller. You need to implement it in your CreateNewAccount class.

CreateNewAccount:

import UIKit

class CreateNewAccount: UIViewController {
    @IBOutlet weak var firstNameInput: UITextField!
    @IBOutlet weak var lastNameInput: UITextField!
    @IBOutlet weak var usernameInput: UITextField!
    @IBOutlet weak var passwordInput: UITextField!

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "thanksForJoining" {
            let destinationVC = segue.destination as! ThanksForJoining
            if
                let firstName = firstNameInput.text, !firstName.isEmpty,
                let lastName = lastNameInput.text, !lastName.isEmpty,
                let username = usernameInput.text, !username.isEmpty,
                let password = passwordInput.text, !password.isEmpty
            {
                destinationVC.receiveUserInfo(firstName: firstName, lastName: lastName, username: username, password: password)
            }
        }
    }
}

ThanksForJoining:

import UIKit

class ThanksForJoining: UIViewController {
    var firstName: String?

    @IBOutlet weak var firstNameLabel: UILabel!

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        firstNameLabel.text = firstName
    }

    func receiveUserInfo(firstName: String, lastName: String, username: String, password: String) {
        print(firstName)
        self.firstName = firstName
    }
}

Seems delegate pattern is sort of too much for your purpose and you just need to define a data passing method in the destination view controller ThanksForJoining.

I assume you have connected your segue from some button of your CreateNewAccount. If the segue is connected from the view controller (not from a button), the code above needs small modification.

But anyway, in your original code, the method prepare(for:sender:) in ThanksForJoining would never be called, so the delegate would never be set. Thus, the delegate remains nil.