Not able to convert the Realtime Database code to Firestore code - ios

Question

I am trying to configure the database for the firestore database, but not able to do so, facing several errors, and not getting any particular solution for that, I am using swift for ios, it is basically a chat app followed from the codelab tutorial, here's the link to the same tutorial! this tutorial is based on Firebase Realtime database, and my requirement is of Firestore database,
thanks in advance for the guidance
What I Tried for converting to firestore database
var messages: [DocumentSnapshot]! = []
fileprivate var _refHandle: CollectionReference!
var ref = Firestore.firestore().collection("messages")
func configureDatabase() {
//ref = Firestore.firestore() // Listen for new messages in the Firebase database
_refHandle = self.ref.addSnapshotListener{ querySnapshot, error in
if let documents = querySnapshot?.documents {
var messages = [DocumentSnapshot]()
for document in documents {
let message = messages(snapshot: document)
message.append(message)
message.clientTable.insertRows(at: [IndexPath(row: message.messages.count-1, section: 0)], with: .automatic)
}
// completion(messages)
}
} as! CollectionReference
}
RealtimeDatabase Code
var ref: DatabaseReference!
var messages: [DataSnapshot]! = []
fileprivate var _refHandle: DatabaseHandle?
deinit {
if let refHandle = _refHandle {
self.ref.removeObserver(withHandle: _refHandle)
}
}
func configureDatabase() {
ref = Database.database().reference()
// Listen for new messages in the Firebase database
_refHandle = self.ref.child("messages").observe(.childAdded, with: { [weak self] (snapshot) -> Void in
guard let strongSelf = self else { return }
strongSelf.messages.append(snapshot)
strongSelf.clientTable.insertRows(at: [IndexPath(row: strongSelf.messages.count-1, section: 0)], with: .automatic)
})
}
Error in firestore Code
Cannot call value of non-function type '[DocumentSnapshot]'"
at
let message = messages(snapshot: document)

Answer 1

This may or may not help but here's a function that reads in all messages and prints the message id (documentId) and the message text to console. Assume we have a class var messsagesArray set up to store each message and a class that hold the documentId and the message text.
Assume this structure
messages //the collection
msg_id_0 //the document id
msgText "Hello"
msg_id_1
msgText:"World"
and the code to read and print the messages
func readAllMessages() {
let messagesCollection = self.db.collection("messages")
messagesCollection.getDocuments(completion: { snapshot, err in
if let err = err {
print(err.localizedDescription)
return
}
for doc in snapshot!.documents {
let key = doc.documentID
let msg = doc.get("msg") as! String
let aMsg = MessageClass(aKey: key, msgText: msg)
self.messagesArray.append(aMsg)
}
for msg in self.messagesArray { //output the read messages to console
print(msg.key, msg.msgText)
}
})
}