Beginner question on passing data between view controllers

Question

I am trying to recreate the Notes app in iOS. I have created an initial View Controller which is just a table view. A user can go to a Detail View Controller to compose a new note with a Title and Body section. When they click Done, I want to manipulate the tableView with note's details.

I am struggling saving the details of what the user entered to use on my initial view controller.

Here's my Notes class which defines the notes data:

class Notes: Codable {
    var titleText: String?
    var bodyText: String?
}

Here is the Detail View controller where a user can input Note details:

class DetailViewController: UIViewController {
    @IBOutlet var noteTitle: UITextField!
    @IBOutlet var noteBody: UITextView!
    
    var noteDetails: Notes?
    var noteArray = [Notes]()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(updateNote))
        noteTitle.borderStyle = .none
    }
    
    @objc func updateNote() {
        noteDetails?.titleText = noteTitle.text
        noteDetails?.bodyText = noteBody.text
        noteArray.append(noteDetails!) // This is nil
                
//        not sure if this is the right way to send the details over
//        let vc = ViewController() 
//        vc.noteArray.append(noteDetails!)
        
        if let vc = storyboard?.instantiateViewController(identifier: "Main") {
        navigationController?.pushViewController(vc, animated: true)
        }
    }
}

I also have an array on my initial view controller as well. I think I need this one to store note data to display in the tableView (and maybe don't need the one on my Detail View controller?). The tableView is obviously not completely implemented yet.

class ViewController: UITableViewController {
    
    var noteArray = [Notes]()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        print(noteArray)
        
        self.navigationItem.setHidesBackButton(true, animated: true)
        
        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .compose, target: self, action: #selector(composeNote))
    }
    
    @objc func composeNote() {
        if let dvc = storyboard?.instantiateViewController(identifier: "Detail") as? DetailViewController {
            
            navigationController?.pushViewController(dvc, animated: true)
        }
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        noteArray.count
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
        
        return cell
    }

user_6577482 · Answer

Just using Delegate: First create delegate protocol with a func to send back note to your viewController

protocol DetailViewControllerDelegate: AnyObject {
    func newNoteDidAdded(_ newNote: Note)
}

Next add the delegate variable to DetailViewController, and call func noteDataDidUpdate to send data back to viewController

class DetailViewController: UIViewController {
    weak var delegate: DetailViewControllerDelegate?

    @objc func updateNote() {
        ....
        delegate?.newNoteDidAdded(newNote)
    }
}

finally, set delegate variable to viewController and implement this in ViewController

class ViewController: UIViewController {

    ....
    @objc func composeNote() {
        if let dvc = storyboard?.instantiateViewController(identifier: "Detail") as? DetailViewController {
            dvc.delegate = self
            navigationController?.pushViewController(dvc, animated: true)
        }
    }

}

extension ViewController: DetailViewControllerDelegate {
    func newNoteDidAdded(_ newNote: Note) {
        // do some thing with your new note
    }
}

Beginner question on passing data between view controllers

1 Answers