Dictionary Changes Index Positions with .keys -- Swift - swift

Question

I'm currently retrieving data from a firebase database, and storing the data in a dictionary. When I try to list the keys in the dictionary like this: snapDict?.keys the indexes of the elements aren't the same as how they are in the database.
Database.database().reference().child("\(UserData().mySchool!)/posts").observeSingleEvent(of: .value, with: { (snapshot) in
print(snapshot.childrenCount)
let snapDict = snapshot.value as? [String: Any]
print(snapshot.value!)
let names = snapDict?.keys
print(names!)
for id in names! {
self.searchNames(id: id)
self.tableView.reloadData()
}
})
This is what the elements that will be in the dictionary look like in the database:
So, you would think when they are put into the dictionary they would be printed as -LJRUC8n........-LOF6JUdm-onVuaq-zij?
snapDict?.keys
prints:
["-LOBSAv_l5_x1xnKwx3_", "-LJRUC8nPF3Vg-DDGiYQ", "-LOBLXpTs39yLZo6EnHl", "-LOF6JUdm-onVuaq-zij", "-LODhXPQi8G7MX1bSfeb", "-LJaUiEnGOcBjKsTWSCS", "-LOBLZzrLAlzkhoidnKf"]
I can't figure out the order/pattern here. Alphabetical? Any ideas why the order turns out this way?

Answer 1

The keys in a dictionary are by definition unordered. So when you convert the snapshot to a dictionary, any information on the order of the nodes is lost.
On top of that, you don't specify an order before reading the data.
To fix both:
Database.database().reference()
.child("\(UserData().mySchool!)/posts")
.queryOrderedByKey()
.observeSingleEvent(of: .value, with: { (snapshot) in
print(snapshot.childrenCount)
for child in snapshot.children.allObjects as! [FIRDataSnapshot] {
print(child.value)
}
})