How to read data from firebase, block with doesn't work? - swift

Question

I try to read data from firebase. I've made observeSingleEvent, but block "with" not works, why?
I try to debug and I notice that block with doesn't work.
userID has correct ID
and reference also correct
var ref: DatabaseReference!
var snapData: NSDictionary?
var nameString = [String]()
override func viewDidLoad() {
super.viewDidLoad()
ref = Database.database().reference()
loadData()
table.delegate = self
table.dataSource = self
table.register(UITableViewCell.self, forCellReuseIdentifier: "indentifire")
view.addSubview(table)
// Do any additional setup after loading the view.
}
// ---------------------------------------------------
//loading data from FireBase
func loadData() {
let userID = Auth.auth().currentUser?.uid
ref.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
self.snapData = snapshot.value as? NSDictionary
})
}
// delegate
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
var temp = 0
for (_,val) in snapData! {
if val as? String == "false" {
temp += 1
nameString.append(val as! String)
}
}
return temp
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = table.dequeueReusableCell(withIdentifier: "indentifire", for: indexPath)
cell.textLabel!.text = nameString[indexPath.row]
return cell
}```
this is my database
![photo](https://imgur.com/a/0UzOPJ7

Answer 1

The database operations work asynchronously. Map the data in loadData and reload the table view
func loadData() {
let userID = Auth.auth().currentUser?.uid
ref.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapData = snapshot.value as? [String:Any] {
self.nameString = snapData.values.compactMap {$0 as? String}
DispatchQueue.main.async {
self.table.reloadData()
}
}
})
}
And in numberOfRowsInSection just return the number of items in nameString
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return nameString.count
}