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

I do not think you want a ChildAdded handler, so I go with a observeSingleEvent example since you want to query data from the database at that time without triggers. When you use a observeSingleEvent, it is important to keep the database in sync. I would recommend using the code below:

query.keepSynched(true) //keeps data in sync with database, if you have data persistince on in your appDelegate
query.observeSingleEvent(of: .value, with: { (snapshot) in //notice the changed here
            print(snapshot)
            //Since you want to loop again because there could be multiple
            //messages in that chatroom which all have a unique ID, do this loop:
            let enumerator = snapshot.children
            while let rest = enumerator.nextObject() as? FIRDataSnapshot {
               //this is 1 single message here
               let values = rest.value as? NSDictionary
               for (key, value) in values{
               print("Key: \(key), value: \(value)") 
               }
               //lets say you want to check if there is a value with a key named "text":
            let textUser = values?["text"] as? String ?? "No text found" 
               //providing a default value if there is no text. You could leave it empty, than it is nil (not recommend)
               //Not only is this a lot more readable, I do not use force unwrapping so your app 
               //cannot cause an exception.

               //Get more values from the dictionary as I did with textUser
               //Initialize message than here. You will see you do not need to force unwrap anything :D
               }

            }

        })