count-down timer not updating .text - ios

Question

Text to count These are the numbers I like to count down, S= start, O= stop, R= reset. Added for simpler functionality but do not want to use them.
I'm trying to set a countdown timer on this app, but I'm having issues getting it to work with the tutorials I've seen. My guess is that this version of swift has different functions, Xcode version 9.4.
The goal is to have a counter for a year, days, and time, as each runs out it stops and counts the next, preferably I want random numbers, no start or stop buttons, start can be once app opens or if the user accepts on a previous screen.
I have tried these methods, but they either don't do anything or force me to use #object func counter(), I believe the timer is not calling the function once its an object, I don't know how to call it.
import UIKit
class ViewController: UIViewController {
var seconds = 30
var timer = Timer()
//these are others I will implement later
#IBOutlet weak var YRS: UILabel!
var yrs = 1
#IBOutlet weak var DAY: UILabel!
var day = 3
#IBOutlet weak var HRS: UILabel!
var hrs = 5
#IBOutlet weak var SEC: UILabel!
var sec = 35
#IBOutlet weak var MIN: UILabel!
//timer function, I believe I have to change #selector as is not
calling the counter func
#IBAction func str(_ sender: UIButton) {
//I have also used just counter but nothing changes :/
timer = Timer.init(timeInterval: 60.0, target: self, selector:
#selector(ViewController.counter), userInfo: nil, repeats: true)
MIN.text = String (seconds)
}
//stop button
#IBAction func sto(_ sender: Any) {
}
//reset button
#IBAction func rst(_ sender: Any) {
}
//counter here -1
#objc func counter(){
seconds -= 1
MIN.text = String(seconds)
if (seconds == 00) {
timer.invalidate()
}
}
override func viewDidLoad() {
super.viewDidLoad()
}
//Something I have tried but did not work
_ = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(UIMenuController.update), userInfo: nil, repeats: true)
}
func update() {
if(min > 0) {
MIN.text = String(min-1)
}
}
//No errors found, the screen is updated with the value but it does not change.

Answer 1

This was a test in Playground. But you can of course also use it in your viewDidLoad Method. It is not ready, you just have to add code where i commented it (add code here...). I set the timer to 0.1 seconds, so that i could test it.
var YRS = UILabel()
var yrs = 1
var DAY = UILabel()
var day = 3
var HRS = UILabel()
var hrs = 5
var SEC = UILabel()
var sec = 35
var MIN = UILabel()
var min = 15
YRS.text = "years \(yrs)"
YRS.sizeToFit()
view.addSubview(YRS)
DAY.text = "day \(day)"
DAY.sizeToFit()
DAY.frame.origin.y = 30
view.addSubview(DAY)
HRS.text = "HRS \(hrs)"
HRS.sizeToFit()
HRS.frame.origin.y = 60
view.addSubview(HRS)
MIN.text = "min \(day)"
MIN.sizeToFit()
MIN.frame.origin.y = 90
view.addSubview(MIN)
SEC.text = "SEC \(sec)"
SEC.sizeToFit()
SEC.frame.origin.y = 120
view.addSubview(SEC)
Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { (timer) in
sec = sec - 1
if sec < 0 { sec = 59
min = min - 1
if min < 0 { min = 59
hrs = hrs - 1
if hrs < 0 {
hrs = 23
HRS.text = "HRS \(hrs)"
HRS.sizeToFit()
// add code here for day ...
}
}
MIN.text = "min \(min)"
MIN.sizeToFit()
}
SEC.text = "sec \(sec)"
SEC.sizeToFit()
}