How to retrieve auto generated documentID from Firestore, to reuse the documentID, so my data isn't replaced

Question

Would like to identify the auto generated id to reference in different query.

{

docRef = db.collection("users").document()

   }

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
  if let document = docRef.documentID.self as? Int ?? {

            let dataDescription = document.data().map(Int.init(describing:)) ?? "nil"
            let profileName = dataDescription["firstname"] as? String ?? ""
            self.nameLabel.text = profileName
            print("Document data: \(profileName)")
    
    }  {
            print("Document does not exist")
        }
    }

Answer 1

Declare the document reference as a property before you create the document:

let userDocRef = Firestore.firestore().collection("users").document()

Then when you need the document ID in a future query, get it from that property:

let docID = userDocRef.documentID

This may require you to pass userDocRef forward to the object that performs the query, or exposing the property to that object. Either way, it's all a matter of scope and how you pass it around or access it is up to your preference.