How can I retrieve data from firebase (Swift) - swift

Question

I am beginner and I would like to use swift as my programming language.
user can add register users and transfer money to each other, therefore when user type the photo number and email, the app can check if the typed number is registered in the firebase system
Any simple way to search if the user exist, thanks a lot
Here's the structure of the database
var ref: DatabaseReference!
var tref: DatabaseReference!
var handle : DatabaseHandle!
var usersArray = [NSDictionary?]()
var filteredUsers = [NSDictionary?]()
var user : NSDictionary?
override func viewDidLoad() {
super.viewDidLoad()
self.picker.isHidden = true
tref = Database.database().reference()
ref = Database.database().reference()
self.handle = self.ref?.child("users").child((Auth.auth().currentUser?.uid)!).child("contact").observe(.childAdded, with: { (snapshot) in
if let item = snapshot.value as? String {
self.pickerdata.append(item)
self.picker.reloadAllComponents()
}
})
self.picker.delegate = self
self.picker.dataSource = self
tref.child("users").queryOrdered(byChild: "phone").observe(.childAdded, with: {(snapshot) in
self.usersArray.append(snapshot.value as? NSDictionary)
})
print(usersArray.count)
}
#IBAction func ContactChange(_ sender: UITextField) {
filteredContent(searchText: contactText.text!)
print(filteredUsers.count)
print(usersArray.count)
print("ARRAY")
}
func filteredContent(searchText: String){
self.filteredUsers = self.usersArray.filter{ user in
let username = user!["phone"] as? String
return (username?.lowercased().contains(searchText.lowercased()))!
}
}
func findUsers(text: String){
self.handle = ref.child("users").queryOrdered(byChild: "phone").queryStarting(atValue: contactText.text!).queryEnding(atValue: contactText.text!+"\u{f8ff}").observe(.value, with: { snapshot in
if let item = snapshot.value as? String {
self.contact.append(item)
} else{
print("error")
}
})
}
The code above doesn't work much. Thanks so much for helping

Answer 1

The question is a little unclear but I think what the OP is asking is:
how to see if a user exists by their phone number?
If that's what's being asked, a node can be retrieved by query'ing for a child of that node. For example, let's create a query on the users node to find the child that contains the name: Kam querying by phone
let usersRef = firebaseRef.child("users")
let query = usersRef.queryOrdered(byChild: "phone").queryEqual(toValue: "2330504")
query.observeSingleEvent(of: .value) { (snapshot) in
if snapshot.exists() {
//need to iterate in case we find more than one match
for child in snapshot.children {
let snap = child as! DataSnapshot
let dict = snap.value as! [String: Any]
let name = dict["name"] as! String
print("found \(name)")
}
} else {
print("not found")
}
}
When this code is run it would print
found Kam
assuming the phone number is 2330504