Image appear when timer is at 1 - swift

Question

im making a reaction time app, and I have a label set to count with Seconds. I want to make my image appear when the label is at 1 second, but it doesn't appear. The timer works fine, just the image. Help me in swift please.
import UIKit
class timerViewController: UIViewController {
var go = NSTimeInterval()
var timer = NSTimer()
#IBOutlet weak var tapStop: UIImageView!
#IBOutlet weak var displayTimer: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
if displayTimer.text == "00:01:00"{
tapStop.image = UIImage(named: "carcrash")
}
}
#IBAction func stop(sender: UIButton) {
timer.invalidate()
}
#IBAction func start(sender: UIButton) {
if (!timer.valid) {
let test:Selector = "updateTime"
timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: test, userInfo: nil, repeats: true)
go = NSDate.timeIntervalSinceReferenceDate()
}
}
func updateTime(){
var timeNow = NSDate.timeIntervalSinceReferenceDate()
var pass: NSTimeInterval = timeNow - go
let minutes1 = UInt8(pass / 60.0)
pass -= (NSTimeInterval(minutes1) * 60)
let seconds1 = UInt8(pass)
pass -= NSTimeInterval(seconds1)
let milli1 = UInt8(pass * 100)
let minutes2 = String(format: "%02d", minutes1)
let seconds2 = String(format: "%02d", seconds1)
let milli2 = String(format: "%02d", milli1)
displayTimer!.text = "\(minutes2):\(seconds2):\(milli2)"
}
}

Answer 1

You should put this:
if displayTimer.text == "00:01:00"{
tapStop.image = UIImage(named: "carcrash")
}
in your func updateTime() instead of viewDidLoad(), and put them into main thread, so that your image will be updated on the UI. Your func updateTime() will look like this:
func updateTime(){
var timeNow = NSDate.timeIntervalSinceReferenceDate()
var pass: NSTimeInterval = timeNow - go
let minutes1 = UInt8(pass / 60.0)
pass -= (NSTimeInterval(minutes1) * 60)
let seconds1 = UInt8(pass)
pass -= NSTimeInterval(seconds1)
let milli1 = UInt8(pass * 100)
let minutes2 = String(format: "%02d", minutes1)
let seconds2 = String(format: "%02d", seconds1)
let milli2 = String(format: "%02d", milli1)
displayTimer!.text = "\(minutes2):\(seconds2):\(milli2)"
if displayTimer.text == "00:01:00"{
dispatch_async(dispatch_get_main_queue(),{
tapStop.image = UIImage(named: "carcrash")
})
}
}