Get All Documents at Once in a Completion Handler with Getdocuments in Firestore

Get all documents at once in a completion handler with getDocuments in Firestore

You only need to enter and leave the dispatch group once for each asynchronous operation. Since (as far as I can see) you only have one getDocuments call, you should only call enter and leave once.

So something like:

let dispatchGroup = DispatchGroup()
var model = [UserModel]()

let db = Firestore.firestore()
let docRef = db.collection("users")
dispatchGroup.enter()
docRef.getDocuments { (querySnapshot, err) in

    for document in querySnapshot!.documents {
        let dic = document.data()
        model.append(UserModel(dictionary: dic))
    }
    dispatchGroup.leave()
}
...

Swift Completion Handler For Loop to be performed once instead of 10 times due to the loop

Use a DispatchGroup. You can enter the dispatch group each time you call the async code and then leave each time it's done. Then when everything is finished it will call the notify block and you can call your handler. Here's a quick example of what that would look like:

let dispatchGroup = DispatchGroup()
let array = []

for i in array {
    dispatchGroup.enter()
    somethingAsync() {
        dispatchGroup.leave()
    }
}

dispatchGroup.notify(queue: .main) {
    handler()
}

Firebase / Firestore - completion block not working as expected

First: I think the main issue is because self.isDone = true is never executed. The reason I think this is because at the time you call fetchData, nrTotalProduse will always be 0, so the execution flow will never enter to the while loop.

Second: You see the cells as they look in the prototypes because numberOfRowsInSection is being called and returning a number that you set to nrTotalProduse, but because the isDone variable is never set to true, cells are not being set with the corresponding value.

Third: The "buggy" scroll you experience is because what you are calling inside the numberOfRowsInSection method. This method will be called whenever you call tableView.reloadData, so what you are doing is keeping a loop of calls that will never end inside this method, resulting in a call to reloadData such many times that you can even see the scroll.

Totally avoid this kind of calls inside the numberOfRowsInSection method.

Edit:

If what you are trying to do is get all the documents in the produse collection, I strongly recommend changing the fetchData method to something like this:

func fetchData() {
    docRef = Firestore.firestore().collection("produse")
    docRef.getDocuments() { (querySnapshot, error) in
        if let error = error {
            print("Error getting documents: \(error)")
        } else {
            for document in querySnapshot!.documents {
                let data = document.data()
                let produs = Produs(denumire: (data?["nume"] as? String)!)
                self.anunturi.append(produs)
            }

            self.isDone = true
            self.tableView.reloadData()
        }
    }
}

Is it possible to have a completion block on the firestore query?

You need to put your signIn INSIDE the getDocuments handler, probably after the for loop?

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