How to parse an ISO-8601 duration in Objective C?

Question

I\'m looking for an easy way to parse a string that contains an ISO-8601 duration in Objective C. The result should be something usable like a NSTimeI

Answer 1

Swift 4.2 version

Works with years, months, days, hours, minutes, seconds. Seconds can be float number.

extension String{
    public func parseISO8601Time() -> Duration {

        let nsISO8601 = NSString(string: self)

        var days = 0, hours = 0, minutes = 0, seconds: Float = 0, weeks = 0, months = 0, years = 0
        var i = 0

        var beforeT:Bool = true

        while i < nsISO8601.length  {

            var str = nsISO8601.substring(with: NSRange(location: i, length: nsISO8601.length - i))

            i += 1

            if str.hasPrefix("P") || str.hasPrefix("T") {
                beforeT = !str.hasPrefix("T")
                continue
            }

            let scanner = Scanner(string: str)
            var value: Float = 0

            if scanner.scanFloat(&value) {

                i += scanner.scanLocation - 1

                str = nsISO8601.substring(with: NSRange(location: i, length: nsISO8601.length - i))

                i += 1

                if str.hasPrefix("Y") {
                    years = Int(value)
                } else if str.hasPrefix("M") {
                    if beforeT{
                        months = Int(value)
                    }else{
                        minutes = Int(value)
                    }
                } else if str.hasPrefix("W") {
                    weeks = Int(value)
                } else if str.hasPrefix("D") {
                    days = Int(value)
                } else if str.hasPrefix("H") {
                    hours = Int(value)
                } else if str.hasPrefix("S") {
                    seconds = value
                }
            }
        }

        return Duration(years: years, months: months, weeks: weeks, days: days, hours: hours, minutes: minutes, seconds: seconds)
}      

Duration struct:

public struct Duration {

let daysInMonth: Int = 30
let daysInYear: Int = 365

var years: Int
var months: Int
var weeks: Int
var days: Int
var hours: Int
var minutes: Int
var seconds: Float

public func getMilliseconds() -> Int{
    return Int(round(seconds*1000)) + minutes*60*1000 + hours*60*60*1000 + days*24*60*60*1000 + weeks*7*24*60*60*1000 + months*daysInMonth*24*60*60*1000 + years*daysInYear*24*60*60*1000
}

public func getFormattedString() -> String{

    var formattedString = ""

    if years != 0{
        formattedString.append("\(years)")
        formattedString.append(" ")
        formattedString.append(years == 1 ? "year".localized() : "years".localized())
        formattedString.append(" ")
    }

    if months != 0{
        formattedString.append("\(months)")
        formattedString.append(" ")
        formattedString.append(months == 1 ? "month".localized() : "months".localized())
        formattedString.append(" ")
    }

    if weeks != 0{
        formattedString.append("\(weeks)")
        formattedString.append(" ")
        formattedString.append(weeks == 1 ? "week".localized() : "weeks".localized())
        formattedString.append(" ")
    }

    if days != 0{
        formattedString.append("\(days)")
        formattedString.append(" ")
        formattedString.append(days == 1 ? "day".localized() : "days".localized())
        formattedString.append(" ")
    }

    if seconds != 0{
        formattedString.append(String(format: "%02d:%02d:%.02f", hours, minutes, seconds))
    }else{
        formattedString.append(String(format: "%02d:%02d", hours, minutes))
    }

    return formattedString
}

}