SpriteKit - TileDefinition and userData being update for all tiles?

I thought I would create a tile map with the new Tile Map Nodes available in iOS 10.

I have a tile which if you stand on it, it will crumble. So I though I would place a userData field called timer in the tileGroup definition.

func crumbleTile(pos :CGPoint, dt : TimeInterval){
        let column = roomMap.tileColumnIndex(fromPosition: pos)
        let row = roomMap.tileRowIndex(fromPosition: pos)
       
        let objectTile = roomMap.tileDefinition(atColumn: column  , row: row)
       
        if var timer = objectTile?.userData?.value(forKey: "timer") as? Double {
            print("tile pos \(column),\(row)")
            print("timer-from tile:\(timer)")
                        timer = timer - dt
            objectTile?.userData?.setValue(timer, forKey: "timer")
            print("timer-update tile:\(timer)")
            if timer < 0.0 {
                //move to next frame
                if var crumbleFrame = objectTile?.userData?.value(forKey: "crumble") as? Int {
                   
                    crumbleFrame = crumbleFrame - 1
                    print("crumble:\(crumbleFrame)")
                    objectTile?.userData?.setValue(crumbleFrame, forKey: "crumble")
                   
                    if crumbleFrame < 1 {
                        //delete tile
                        print("delete tile")
                        removeTile(pos: pos)
                    } else {
                        //move to next frame
                        print("next frame")
                       
                        if crumbleFrame == 2 {
                            print("change frame 2")
                           
                           
                        }
                        if crumbleFrame == 1 {
                            print("change frame 1")
                           
                           
                        }
                        if crumbleFrame == 0 {
                            print("change frame 0")
                        }
                    }
                }
            }
        }
    }
    func removeTile(pos : CGPoint) {
        let column = roomMap.tileColumnIndex(fromPosition: pos)
        let row = roomMap.tileRowIndex(fromPosition: pos)
                 roomMap.setTileGroup(nil, forColumn: column, row: row)
    }

Instead of each tile having it's own timer setting it appear that I am either adjusting a single timer or simultaneously adjust every timer for that tile.

It can be seen in the log file.

tile pos 51,11

timer-from tile:-0.104295339999993

timer-update tile:-0.125737270999991

crumble:-1

delete tile

2:crumble floor right

tile pos 52,11

timer-from tile:-0.125737270999991

timer-update tile:-0.164520885999991

crumble:-2

delete tile

tile at position 52,11 has the same timer value as 52,11 had ?

So the question is, is there a way to individually access each tiles userData ?

Thanks in Advance.