How to read data from FireBase - ios

Question

I have problem reading from Firebase in Swift.
Here is my Firebase database:
and here is my code:
var ref: FIRDatabaseReference!
override func viewDidLoad() {
super.viewDidLoad()
NSLog("Reading from DB")
ref = FIRDatabase.database().reference()
self.ref?.child("Frais").observeSingleEvent(of: .value, with: { (snapshot) in
let value = snapshot.value as? [String: Int]
var frpx1 = (value?["frpx1"]!)!
var frpx10 = (value?["frpx10"]!)!
var frpx11 = (value?["frpx11"]!)!
var frpx12 = (value?["frpx12"]!)!
var frpx13 = (value?["frpx13"]!)!
var frpx14 = (value?["frpx14"]!)!
var frpx15 = (value?["frpx15"]!)!
var frpx16 = (value?["frpx16"]!)!
})
print(frpx1)
print(frpx10)
print(frpx11)
print(frpx12)
print(frpx13)
print(frpx14)
print(frpx15)
print(frpx16)
}
I did not find the problem.
I do not have the data from database in frpx1, ..., frpx16.

Answer 1

Your code have a couple of minor issues:
you are casting the returned value to [String: Int] when you should be using [String: Any] instead since not all values are String based.
you are printing the results outside the completion handler. You need to wait the handler to be called to then read the results (i.e., when the method observeSingleEvent returns Firebase is still processing your request).
Fixing both issues should get you going:
...
self.ref?.child("Frais").observeSingleEvent(of: .value, with: {
(snapshot) in
guard let value = snapshot.value as? [String: Any] else {
print("Snapshot type mismatch: \(snapshot.key)")
return
}
let frpx1 = value["frpx1"]
let frpx10 = value["frpx10"]
let frpx11 = value["frpx11"]
...
print(frpx1)
print(frpx10)
print(frpx11)
...
})
PS. I also improved your coding style a little to help prevent further issues ;)