Q:

Firebase multi-path update with childByAutoId possible? 

Is it possible to use the multi-path update feature for Firebase in combination with creating child nodes (with auto-id)? 
So far I have found only solution for updates where the full path is known only. 
e.g.
var newData = [String: AnyObject]()
newData["conversations/messages/<placeholder for new id>"] = newMessage
newData["conversations/somethingDifferent"] = additionalData
...

A:

Push-ids are generated on the client.  childByAutoId returns a new Firebase, but without sending data over the network. 
let ref = Firebase(url: "<my-firebase-app>")
let childRef = ref.childByAutoId()

var newData = [String: AnyObject]()
newData["conversations/messages/\(childRef.key)"] = newMessage

Once you've created a child reference, you can just use its key in the dictionary for the multi-path update.