CODEWITHSUNDEEP
swiftfirebasefirebase-realtime-databaseseguejsqmessagesviewcontroller
micyukcha
micyukcha

Reputation: 367

Segue async Firebase data through NavigationController (Swift)

I have been chasing this for two days but yet I am still not sure why my variable isn't being passed in my segue from my login view controller to the chat view controller via the navigation view controller.

I have a button that queries Firebase, checks if the user exists and returns a Firebase query reference for the user. I then want to pass this Firebase query reference when it finishes to the navigation controller's top view controller for use.

Inside my IBAction login button, I have:

    var tempUserRef: FIRDatabaseReference?

    channelRef.queryOrdered(byChild: "uid").queryEqual(toValue: uid).observeSingleEvent(of: .value, with: { (snapshot) in
        if snapshot.exists() {
            print("uid exist with \(snapshot.childrenCount) number of children")

            for s in snapshot.children.allObjects as! [FIRDataSnapshot] {
                tempUserRef = self.channelRef.child(s.key)
            }

        } else {
            print("uid didn't exist")

            if let name = self.nameField?.text { // 1
                tempUserRef = self.channelRef.childByAutoId()

                let channelItem = [
                    "name": name,
                    "uid": self.uid
                ]
                tempUserRef?.setValue(channelItem)
            }
        }
        self.userRef = tempUserRef
        DispatchQueue.main.async {
            self.performSegue(withIdentifier: "LoginToChat", sender: tempUserRef)
            print("passsed \(self.userRef)")

        }
    })

Here is my segue:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if "LoginToChat" == segue.identifier {
            if let navVc = segue.destination as? UINavigationController {
                if let chatVc = navVc.topViewController as? ChatViewController {
                    chatVc.senderDisplayName = nameField?.text
                    if let userRef = sender as? FIRDatabaseReference {
                        chatVc.userRef = userRef
                        print("passsing \(self.userRef) to \(chatVc)")
                    }
                }
            }
        }
        super.prepare(for: segue, sender: sender)
    }

The print statements all look good on my login controller but when I get to the chat view controller, the userRef is still nil. So my sense is that I have the right segue inputs and handoffs but that the async nature of the data is somehow out of step with my segue.

The chat view controller is using the JSQMessages library if that makes a difference.

Thanks for your help.

EDIT: Based off feedback I've moved the super.prepare but userRef is still not being set consistently.

SECOND EDIT: Following paulvs' suggestion, I removed my button segue. However, I did have to create another segue that connected view controller to view controller like this SO question.

Upvotes: 0

Views: 262

Answers (1)

paulvs
paulvs

Reputation: 12053

Place the call to super.prepare at the end of the function. Otherwise, the segue is performed before you set your variables.

Upvotes: 1

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