Use of local variable 'updateTimer' before its declaration Egg timer - xcode

Question

I just started learning programming and the instructor asked us to make an egg timer app.
I tried to run her example solution but XCode shows an issue with the code at #selector(updateTimer). The error says Use of local variable 'updateTimer' before its declaration.
This is the code:
class ViewController: UIViewController {
#IBOutlet weak var progress: UILabel!
let eggTimes = ["Soft" :3, "Medium":4, "Hard":6]
var secondsRemaining = 60
var timer = Timer()
#IBAction func hardnessSelected(_ sender: UIButton) {
timer.invalidate()
let hardness = sender.currentTitle!
secondsRemaining = eggTimes[hardness]!
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector:
#selector(updateTimer), userInfo: nil, repeats: true)
func updateTimer() {
if secondsRemaining > 0 {
print("\(secondsRemaining) seconds left to finish")
secondsRemaining -= 1
}
else {
timer.invalidate()
progress.text = "DONE"
}
}
}
}

Answer 1

The issue you're having is that the func updateTimer is declared under the #selector and as such isn't "available yet" to put it simply. What you probably wanted is to move the function outside the hardnessSelected as such:
class ViewController: UIViewController {
#IBOutlet weak var progress: UILabel!
let eggTimes = ["Soft" :3, "Medium":4, "Hard":6]
var secondsRemaining = 60
var timer = Timer()
#IBAction func hardnessSelected(_ sender: UIButton) {
self.timer.invalidate()
let hardness = sender.currentTitle!
self.secondsRemaining = self.eggTimes[hardness]!
self.timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.updateTimer), userInfo: nil, repeats: true)
}
#objc func updateTimer() {
if self.secondsRemaining > 0 {
print("\(self.secondsRemaining) seconds left to finish")
self.secondsRemaining -= 1
}
else {
self.timer.invalidate()
self.progress.text = "DONE"
}
}
}
You also need to add #objc in front of the function name to expose it to ObjC runtime. You can read more about that here.