Retrieve String value from function with closure in Swift

Question

I am trying to retrieve a string value from Firebase in order to get each username with an unique UID that is passed to the function, which returns the username of the user.

Answer 1

You need to create completion handler like this

func GetUsername(uid:String , completion: (String) -> ()) {
    firebase.child("Users").child(uid).observeSingleEventOfType(.Value) { (snapshot:FIRDataSnapshot) in
    if let username = snapshot.value!["Username"] as? String
        completion(username)
    }
    else {
        completion("")
    }
}

And call function like this way

self.GetUsername(str) { (name) -> () in
    if name.characters.count > 0 {
         print(name)
    }
    else {
         print("Not found")
    }
}