Getting all the users same child in Firebase (Swift) - ios

Question

I am currently building an app in Firebase and I want to get all the users pineapple rate.
This is the tree:
user1: uid1 {
fruits: {
apple: 3
pineapple: 5
}
}
user2: uid2 {
fruits: {
apple: 4
pineapple: 2
}
}
I tried this code:
var ref = FIRDatabase.database().reference()
ref.queryOrderedByChild("fruits")
.observeSingleEventOfType(.Value, withBlock: { (snapshot) in
if ( snapshot.value is NSNull ) {
print("not found")
} else {
for child in snapshot.children {
let rate = child.value["pineapple"] as! String
print(rate)
}
}
})
But it gives me an error of unwrapping Nil.
Picture of the structre:

Answer 1

This is supposed to be like this
var ref = FIRDatabase.database().reference()
ref.queryOrderedByChild("user2")
.observeSingleEventOfType(.Value, withBlock: { (snapshot) in
if snapshot.exists() {
for child in (snapshot.value?.allValues)! {
if let fruits = child["Fruits"] as? [String:String]{
let rate = fruits["pineapple"]
print(rate)
}
}
}
})

Answer 2

It seems this just needs a deep query?
let ref = self.myRootRef.child("parent_node")
ref.queryOrderedByChild("Fruits/pineapple").observeSingleEventOfType(.Value, withBlock: {
snapshot in
if ( snapshot.value is NSNull ) {
print("not found")
} else {
for child in snapshot.children {
let key = child.key as String
let dict = child.value["Fruits"] as! NSDictionary
let pineapple_count = dict["pineapple"] as! Int
print("key = \(key) count = \(pineapple_count)")
}
}
})
and the output is
key = uid_1 count = 1
key = uid_0 count = 3
key = uid_2 count = 21

Answer 3

Try out this code below (Xcode 8.3.3, Swift 3 and Firebase 3 )
var ref = Database.database().reference().child("fruits")
ref.observeSingleEvent(of: .value, with: {
(snapshot) in
if let fruitPost = snapshot.value as? Dictionary<String,AnyObject> {
for(key, value) in fruitPost {
if let fruitData = value as? Dictionary<String,AnyObject> {
if let fruits = fruitData["pineapple"] as? String{
let rate = fruits
print(rate)
}
}
}
}
Goodluck mate!