Timer Issue / explanation

[scy]

I am trying to update the label with the current Time.

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var label: UILabel!
    let date = Date()

    override func viewDidLoad() {
        super.viewDidLoad()
        
        Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateTime), userInfo: nil, repeats: true)
    }
    
    
    func updateTime(){
        
        label.text = DateFormatter.localizedString(from: Date(), dateStyle: .none, timeStyle: .long)
        
    }
    

}

when I am using at updateTime() label.text = DateFormatter.localizedString(from: Date(), dateStyle: .none, timeStyle: .long) I am getting the result that I want

When I am using label.text = DateFormatter.localizedString(from: date, dateStyle: .none, timeStyle: .long)

the timer is not working. can someone please explain me ? ?

From my understanding I if I use a date and not Date() then I need a timer to count and calculate. If so any suggestions ?

[nikita_gaydukov]

Hi @scy

What do you mean by “timer is not working”? Your updateTime() function will trigger no matter what you put in your DateFormatter.localizedString parameters. Do you have a crash or error or something else?

Nikita

[scy]

Hi @nikita_gaydukov

When I use Date() in DateFormatter.localizedString(from Date(), . . . . .) it works and it prints every second the value from Date()

But when you pass the constant let date = Date() meaning DateFormatter.localizedString(from: date , …) then it is just updating the same constant since it is not updating.

My question if I can make it completely clear is **How I can make a constant type Date like let date = Date() make it start showing a count up from the time that is getting the let date = Date() and then count up in a label?

example : assume that date = 2017-08-07 04:00:00 as Date

how I can make this constant showing in a label a count up like
2017-08-07 04:01:00
2017-08-07 04:02:00
2017-08-07 04:03:00

or even seconds

Thanks a lot !!

[nikita_gaydukov]

Hi @scy

In general the Timer class is not accurate for this sort of things, so you cannot rely on just incrementing date (because your updateTime func woudn’t be called every ~1 second, but not exactly every 1 second).
If i understood your question correctly, you will need to store the date when your timer actually started, then on every timer tick check the difference between the timer start date and a current date, then add that difference to your your date constant. This way you will have the accurate timer.

Nikita

[scy]

Hi Nikita and thanks fro your Answer again. Yes that was the question and you are right.

Thumbs up !