Fetch Firebase child data in Swift - ios

Question

I already have setup Firebase on Xcode 9.
My question:
I want to retrieve data from Firebase. This works but when I add another text in a group it wont retrieve.
Example
FIREBASE:
lang :
"Deutsch"
"Englisch"
Firebase Image Example because it's difficult to explain:
import UIKit
import FirebaseDatabase
class ViewController: UIViewController {
#IBOutlet weak var outputone: UILabel!
// #IBOutlet weak var outputtwo: UILabel!
var dbReference: DatabaseReference?
var dbHandle: DatabaseHandle?
override func viewDidLoad() {
super.viewDidLoad()
dbReference = Database.database().reference()
// dbReference?.child("lang").childByAutoId().setValue("Deutsch")
// dbReference?.child("lang").childByAutoId().setValue("Englisch")
// retrieve data
dbHandle = dbReference?.child("lang").observe(.childAdded, with:{ (snapshot) in
let lang:String? = snapshot.value as? String
self.outputone.text = (lang)
})
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
I want that "Deutsch" displays in outputone and "Englisch" in outputtwo
Can someone help ?

Answer 1

Right now you retrieve the entire lang node. So the snapshot you get from Firebase contains both "de": "Deutch" and "en": "English". When you now do snapshot.value as? String, it returns nil since the snapshot doesn't have a single, simple string value.
To get the specific values, you first need to tell the snapshot which child property you want: de or en, and then you can get the string value.
dbHandle = dbReference?.child("lang").observe(.value, with:{(snapshot) in
let de:String? = snapshot.childSnapshot(forPath:"de").value as? String
let en:String? = snapshot.childSnapshot(forPath:"en").value as? String
self.outputone.text = (de)
self.outputtwo.text = (en)
})

Answer 2

when retrieving the data from Firebase, it's come as a chunk. This is when the downCasting comes in handy.
dbHandle = dbReference?.child("lang").observe(.childAdded, with:{(snapshot) in
guard let dictionary = snapshot.value as? [String:Any],
let de = dictionary["de"] as? String,
let en = dictionary["en"] as? String else {
"error occurs when down casting.."
return}
self.outputone.text = de
self.outputwo.text = en
})
whenever dealing with a dictionary approach, it's dangerous to hardcode string key every time. it's error-prone. I recommend you create a struct holding each key so you don't need to type string every time needed.