Реализовать отсчет от текущей даты

Подскажите, пожалуйста. Хочу реализовать отсчет лет, месяцев, дней, часов, минут и секунд от определенной даты до текущей. Этот отсчет хочу показывать в лейбле с обновлением в 1 секунду. К примеру : 2 года, 11 месяцев, 16 дней, 7 часов, 42 минут, 40 секунд

Реализовал такой код:

class CompletionTimeDifference {
    
    static let shared = CompletionTimeDifference()
    
    let date = NSDate()
    let calendar = Calendar.current

    func getDifference(year: Int, month: Int, day: Int, hour: Int, minute: Int, second: Int) -> String {
        let components = calendar.dateComponents([.hour, .minute, .second, .month, .year, .day], from: date as Date)

        let currentDate = calendar.date(from: components)

        let userCalendar = Calendar.current

        let competitionDate = NSDateComponents()
        
        competitionDate.year = year
        competitionDate.month = month
        competitionDate.day = day
        competitionDate.hour = hour
        competitionDate.minute = minute
        competitionDate.second = second
        
        let competition = userCalendar.date(from: competitionDate as DateComponents)!

        let CompetitionDifference = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: currentDate!, to: competition)

        let yearsLeft = (CompetitionDifference.year ?? 0) * -1
        let monthsLeft = (CompetitionDifference.month ?? 0) * -1
        let daysLeft = (CompetitionDifference.day ?? 0) * -1
        let hoursLeft = (CompetitionDifference.hour ?? 0) * -1
        let minutesLeft = (CompetitionDifference.minute ?? 0) * -1
        let secondsLeft = (CompetitionDifference.second ?? 0) * -1
        
        var years = "\(yearsLeft)"
        var months = "\(monthsLeft)"
        var days = "\(daysLeft)"
        var hours = "\(hoursLeft)"
        var minutes = "\(minutesLeft)"
        var seconds = "\(secondsLeft)"
        
        if yearsLeft.words.last == 1 {
            years = years + " год"
        }
        else if yearsLeft.words.last == 2 || yearsLeft.words.last == 3 || yearsLeft.words.last == 4 {
            years = years + " года"
        } else {
            years = years + " лет"
        }
        if monthsLeft.words.last == 1 {
            months = months + " месяц"
        }
        else if monthsLeft.words.last == 2 || monthsLeft.words.last == 3 || monthsLeft.words.last == 4 {
            months = months + " месяца"
        } else {
            months = months + " месяцев"
        }
        if daysLeft.words.last == 1 {
            days = days + " день"
        }
        else if daysLeft.words.last == 2 || daysLeft.words.last == 3 || daysLeft.words.last == 4 {
            days = days + " дня"
        } else {
            days = days + " дней"
        }
        if hoursLeft.words.last == 1 {
            hours = hours + " час"
        }
        else if hoursLeft.words.last == 2 || hoursLeft.words.last == 3 || hoursLeft.words.last == 4 {
            hours = hours + " часа"
        } else {
            hours = hours + " часов"
        }
        if minutesLeft.words.last == 1 {
            minutes = minutes + " минута"
        }
        else if minutesLeft.words.last == 2 || minutesLeft.words.last == 3 || minutesLeft.words.last == 4 {
            minutes = minutes + " минуты"
        } else {
            minutes = minutes + " минут"
        }
        if secondsLeft.words.last == 1 {
            seconds = seconds + " секунда"
        }
        else if secondsLeft.words.last == 2 || secondsLeft.words.last == 3 || secondsLeft.words.last == 4 {
            seconds = seconds + " секунды"
        } else {
            seconds = seconds + " секунд"
        }
        
        return "\(years), \(months), \(days), \(hours), \(minutes), \(seconds)"
    }

Далее во вьюконтроллере через таймер пытаюсь вывести дату в лейбл, но у меня не обновляется он, а показывает только одну дату (как при единоразовом вызове функции)

Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateTimeLabel), userInfo: nil, repeats: true)

@objc func updateTimeLabel() {
        counterLabel.text = timeDifference.getDifference(year: 2020, month: 1, day: 1, hour: 9, minute: 0, second: 0)
     }