Variable scope not what I want it to be?

Question

I have a function bellow called retrieveUsers() which is called inside a function which fetches all posts under a Post node.

Inside the code found bellow I save the current UID to a variable with global scope. But every time this function gets called the variable (lastUID) seems to be reset. Even though this method is being called in a for-loop essentially.

 func retrieveUsers(value: Post) {
    print(lastUID, "-=-=--=-=")
    print(value.user.userID != lastUID, ": ", value.user.userID!, " email left old ... one -> ", lastUID)

    if value.user.userID != lastUID {//Ignore this line
        let ref = Database.database().reference()
        if value.user.userID != nil {
            let UID = value.user.userID!
            print(UID, "Thoi s is the uid in the users fetch fx")
            ref.child("users2").child(UID).observe(.value, with: { (snapshot) in
                let email = "\(snapshot.childSnapshot(forPath: "email").value as! String)"
                do {
                    value.user.email = email
                    //even with the two values being in here the same thing happens
                }
                self.lastUID = UID
                self.lastEmail = email
            })
        }
    } else {
        print("ESC this is the same user")
        value.user.email = lastEmail
    }
}

What is going wrong?

Data is loaded from Firebase asynchronously. You need to make sure that all code that needs the data is inside the closure (or called from there). See https://stackoverflow.com/questions/43823808/access-firebase-variable-outside-closure, https://firebase.googleblog.com/2018/07/swift-closures-and-firebase-handling.html, https://stackoverflow.com/questions/40904141/access-data-outside-of-closure-firebase-observesingleevent-swift/40952103#40952103 — Frank van Puffelen, Mar 02 '19 at 21:44

score 0 · Accepted Answer · answered Mar 02 '19 at 21:45

0

Even though this method is being called in a for-loop essentially.

The global var is changed every cycle of the for - loop and since the calls to firebase are asynchronous , hence you can't catch every fetch with it's corressponding UID

You need to create a model and make those calls inside it with a property as the uid

answered Mar 02 '19 at 21:45

Shehata Gamal

98,760
8
65
87

So you are saying that the value can only exist if inside the closure or if saved to a object which can store the value? So despite it being saved to the gloabal variable, for some reason the code will not keep the value i storage? – Mar 02 '19 at 21:50
yes ,,,,,, the for loop overrides the value before your response returns from firebase – Shehata Gamal Mar 02 '19 at 21:51

Variable scope not what I want it to be?

1 Answers1