How do I check if a firebase database value exists?

I'm using the Realtime Database with Google's Firebase, and I'm trying to check if a child exists.

My database is structured as the following

- / (root)
-   /users/
–-    /james/
--    /jake/
-   /rooms/
--    /room1/
---      (room 1 properties)
--    /room2/
---      (room 2 properties)

I would like to check if room1 exists. I have tried the following:

let roomName:String = "room1"
roomsDB.child(roomName).observeSingleEventOfType(.Value) { 
(snap:FIRDataSnapshot) in
    let roomExists:Bool = snap.value != nil ? "TAKEN" : "NOT TAKEN"
 }

In accessing snap.value it returns a JSON of the properties of that room, but how would I check if the room (/rooms/room1/) is there to begin with?

Comment if any clarification is needed

Solution 1:

self.ref = FIRDatabase.database().reference()

   ref.child("rooms").observeSingleEvent(of: .value, with: { (snapshot) in

        if snapshot.hasChild("room1"){

            print("true rooms exist")

        }else{

            print("false room doesn't exist")
        }


    })

Solution 2:

While the answer of @ismael33 works, it downloads all the rooms to check if room1 exists.

The following code accomplishes the same, but then only downloads rooms/room1 to do so:

ref = FIRDatabase.database().reference()

ref.child("rooms/room1").observeSingleEvent(of: .value, with: { (snapshot) in
    if snapshot.exists(){
        print("true rooms exist")
    }else{
        print("false room doesn't exist")
    }
})