how to do a if else statement on time intervals in swift 3

Right now my app has a timer that runs in seconds. I would like the code to work as this. If the time =< 10 then display image a else display image b.

if green {

            timer.invalidate()
            startStop.isEnabled = true
            scoreTimer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(ViewController.updateScoreTime), userInfo: nil, repeats: true)

          I WOULD LIKE THE CODE FOR THE =<10 then display image a else display b. TO GO HERE

        }