Passing documentID of Firestore using segue in Swift

Question

I'm learning both Swift and firebase by making an app. In my current firestore, I have a database with collection name Players, and inside of the collection, there is a document with auto-documentID and two fields, such as name and email. Like this. firestore image

I also use Firebase Auth, so whenever a user makes an account I put their email into firestore with field name email.

Here is the code for RegisterViewController where a user register their account with email and password.

import UIKit
import Firebase

class RegisterViewController: UIViewController {


    @IBOutlet weak var emailTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!

    let db = Firestore.firestore()

    override func viewDidLoad() {
        super.viewDidLoad()

    }



    //MARK: - register a new account

    @IBAction func registerPressed(_ sender: UIButton) {
    
        if let email = emailTextField.text, let password = passwordTextField.text {
        
            Auth.auth().createUser(withEmail: email, password: password) { authResult, error in
            
            
                if error != nil {
                
                // some codes here
                
                
                } else {
                
                    // Add a new document with a generated ID
                    var ref: DocumentReference? = nil
                
                    ref = self.db.collection(K.FStore.playersCollection).addDocument(data: [K.FStore.emailField: email, K.FStore.nameField: ""]) { (error) in
                    
                        if let err = error {
                            print("There was an issue storing data to firestore. \(err)")
                        } else {
                            print("Document added with ID: \(ref!.documentID)")
                        }
                    }
                
                    // pass this data
                
                    func prepare(for segue: UIStoryboardSegue, sender: Any?) {
                        if segue.identifier == K.registerToHome {
                            let homeVC = segue.destination as! HomeViewController
                        
                            homeVC.documentID = ref?.documentID
                        }
                    }
                
                     self.performSegue(withIdentifier: K.registerToHome, sender: self)
                
                }
            
            }
        
        }
    }



}

I'm planning to check if the user has a name in their document name field in the next HomeViewController, so if the value of the name field in the document is "", I want to display an alert with a textfeild, so the user can add their name. However, in the HomeViewController, I need the documentID because I will use this code, db.collection(K.FStore.playersCollection).document(documentID).getDocument in HomeVC, so I want to pass the user's documentID (in the RegisterVC, I was able to get the value as ref?.documentID, so I just want to pass the value to HomeVC) to HomeVC. I tried using func prepare(for segue: UIStoryboardSegue, sender: Any?), but I was not able to pass the value...

Answer 1

Change your code to :

//Top of the your code define id :

var id = ""

else {
   // Add a new document with a generated ID
   var ref: DocumentReference? = nil
            
   ref = self.db.collection(K.FStore.playersCollection).addDocument(data: [K.FStore.emailField: email, K.FStore.nameField: ""]) { (error) in
                
       if let err = error {
          print("There was an issue storing data to firestore. \(err)")
       } else {
          print("Document added with ID: \(ref!.documentID)")
          self.id = ref!.documentID 
          self.performSegue(withIdentifier: K.registerToHome, sender: self)
       }
   }   
}

//Out of registerPressed func :

// pass this data
            
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
   if segue.identifier == K.registerToHome {
        let homeVC = segue.destination as! HomeViewController
                    
         homeVC.documentID = self.id
   }
 }