swift - How to display data from Firebase faster?

Question

I have label and data from Firebase. I need to get the data, count it and update Label. But I have problem. I get the data later than I start counting it.

 let uid = Auth.auth().currentUser?.uid
        let ref = Database.database().reference()
        ref.child("users").child(uid!).child("weight").observe(.value) { (snapshot) in
            self.userWeight = snapshot.value as! Float
            print(self.userWeight)
        }

Than I should count it and display.

self.maxAmountOfWater = (self.userWeight * 4) / 100
maxWaterLabel.text = String(maxAmountOfWater)

Value of Label is 0 because I fetch data slow. I do it all in viewDidLoad

Answer 1

Waitting for answers