Firebase Query snapshot nil?

Question

I\'m creating a simple chat app to learn Swift and Firebase. I have a query that checks for a chat room\'s messages to load into a tableView. The query returns a snapshot bu

Answer 1

As Pipiks explained, your issue is that you are attempting to access individual message details at one level higher than the returned data.

The snapshot value is giving you a dictionary of chat messages, where the top level's keys are the chat message keys. To map your returned data to an array of messages, I would use the following code:

query.observeSingleEvent(of: .childAdded, with: { snapshot in

    guard let messagesDict = snapshot.value as? [String: AnyObject] else { return }

    self.messages = messagesDict.flatMap({ (messageId: String, messageData: Any) -> Message? in
        guard
            let sender = messageData["sender"] as? String,
            let text = messageData["text"] as? String,
            let timestamp = messageData["timestamp"] as? Int,
            let message = Message(key: messageKey, sender: sender, text: text, timestamp: timestamp) else {
                return nil
        }
        return message
    })

    self.tableView.reloadData()
})

What this does is map your dictionary of messages to an array of Message objects.

I have used a flatMap to filter out any messages which do not have sender, text or timestamp values (so the flatMap returns a [Message] object).

Does that solve the issue?