Get the word "Month", "Day", "Week" localized

Where do you get "month" in the date display ?

Could you show an example of how you get the date, how you localize, how you set locale and what you get with "month" inside.

If you write "month" as a string you define yourself, yes, you need NSLocalized.

Finally found the solution by myself with:

extension Calendar {

    /// get a calendar configured with the language of the user
    static var localized: Calendar {
        let prefLanguage = Locale.preferredLanguages[0]
        var calendar = Calendar(identifier: .gregorian)
        calendar.locale = Locale(identifier: prefLanguage)
        return calendar
    }
    
     func unitTitle(_ unit: NSCalendar.Unit, value: Int = 1, locale: Locale? = nil) -> String {
        let emptyString = String()
        let date = Date()
        let component = getComponent(from: unit)
        guard let sinceUnits = self.date(byAdding: component, value: value, to: date) else {
            return emptyString
        }

        let timeInterval = sinceUnits.timeIntervalSince(date)
        let formatter = DateComponentsFormatter()

        formatter.calendar = self
        formatter.allowedUnits = [unit]
        formatter.unitsStyle = .full
        guard let string = formatter.string(from: timeInterval) else {
            return emptyString
        }

        return string.replacingOccurrences(of: String(value), with: emptyString).trimmingCharacters(in: .whitespaces).capitalized
    }
    
    // swiftlint:disable:next cyclomatic_complexity
    private func getComponent(from unit: NSCalendar.Unit) -> Component {
        let component: Component

        switch unit {
        case .era:
            component = .era
        case .year:
            component = .year
        case .month:
            component = .month
        case .day:
            component = .day
        case .hour:
            component = .hour
        case .minute:
            component = .minute
        case .second:
            component = .second
        case .weekday:
            component = .weekday
        case .weekdayOrdinal:
            component = .weekdayOrdinal
        case .quarter:
            component = .quarter
        case .weekOfMonth:
            component = .weekOfMonth
        case .weekOfYear:
            component = .weekOfYear
        case .yearForWeekOfYear:
            component = .yearForWeekOfYear
        case .nanosecond:
            component = .nanosecond
        case .calendar:
            component = .calendar
        case .timeZone:
            component = .timeZone
        default:
            component = .calendar
        }
        return component
    }
}

And the use is:

Calendar.localized.unitTitle(.day)
Calendar.localized.unitTitle(.weekofMonth)
Calendcar.localized.unitTitle(.month)

Just add 3 days to timeInterval if the unit is month to accommodate varying month lengths.

        var timeInterval = sinceUnits.timeIntervalSince(date)
        if unit == .month {
            timeInterval = timeInterval.advanced(by: .days(3))
        }

I managed to do it using this:

func localizedUnit(for unit: Unit, locale: Locale) -> String {

    let numberFormatter = NumberFormatter()
    numberFormatter.notANumberSymbol = ""

    let formatter = MeasurementFormatter()
    formatter.unitStyle = .long
    formatter.numberFormatter = numberFormatter
    formatter.locale = locale

    return formatter.string(from: Measurement(value: .nan, unit: unit))
}

Following up my previous comment (still being approved)

A more type-safe version:

enum UnitSymbol: String {
  case month
  case week
  case day
}

func localizedUnit(for unitSymbol: UnitSymbol, locale: Locale) -> String {

    let numberFormatter = NumberFormatter()
    numberFormatter.notANumberSymbol = ""

    let formatter = MeasurementFormatter()
    formatter.unitStyle = .long
    formatter.numberFormatter = numberFormatter
    formatter.locale = locale

    return formatter.string(from: Measurement(value: .nan, unit: Unit(symbol: unitSymbol.rawValue)))
}