The timer is terminated when the view changes - swift

Question

I am not a native English speaker and I am writing with a translator.
I want you to understand if the context is strange.
My Question is,
When the button is pressed, the timer operates, but when the view is switched, the timer is not operating.
I wonder how the timer can be maintained even if the view changes.
var time : Int = 0
var onehour : Int = 60
var timer = Timer()
#IBAction func pressSuncream(_ sender: Any) { // Suncream 버튼
useSuncream.setImage(UIImage(named: "test"), for: UIControlState.normal)
if #available(iOS 10.0, *) {
let content = UNMutableNotificationContent()
content.title = "hello"
content.body = "timer"
content.badge = 1
let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 3600, repeats: false)
let request = UNNotificationRequest(identifier: "timerdone", content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)
timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(QuestView.updatetime), userInfo: nil, repeats: true)
} else {
// Fallback on earlier versions
}
}
func updatetime() {
time += 1
if time == 60 {
time = 0
onehour -= 1
DispatchQueue.main.async {
self.suncreamTime.text = String(self.onehour)
}
}
}

Answer 1

when you switch to the mainView,you can store the value of onehour in the UserDefaults at the override func viewWillDisappear(_ animated: Bool) { }.
when you into the timerView,you can get the value at the override func viewWillAppear(_ animated: Bool) {}
eg:
override func viewWillDisappear(_ animated: Bool) {
let userDefault = UserDefaults.standard
userDefault.set(onehour, forKey: "onehour")
}
override func viewWillAppear(_ animated: Bool) {
if let onehour = UserDefaults.standard.value(forKey: "onehour") {
self.onehour = onehour as! String
}
}

Answer 2

One way that you could do this, is to make the timer variable global. This is probably a "dirty" way to do it, and if there really are terrible ramifications of doing this, someone let me know and I'll take this down.
Essentially all you would need to do is define it outside of any class like so:
var timer: NSTimer?
class MyClass: UIViewController {
...
}
This way you can access it from any file. I would say that you are generally discouraged from doing this unless you have to, so it's more of a last-resort option.