swift：计算时间差

//获取日期差，yyyy-MM-dd HH:mm:ss格式

func intervalSinceNow(_ fromdate:Date) -> String{

    let format = DateFormatter.init()

    format.dateFormat ="yyyy-MM-dd HH:mm:ss"

    

    let fromZone = TimeZone.current

    let fromInterval = fromZone.secondsFromGMT(for: fromdate)

    let fromDate = fromdate.addingTimeInterval(Double(fromInterval))

    

    let adate = Date()

    let zone =TimeZone.current

    let interval = zone.secondsFromGMT(for: adate)

    let localeDate = adate.addingTimeInterval(Double(interval))

    

    let interValTime = fromDate.timeIntervalSinceReferenceDate - localeDate.timeIntervalSinceReferenceDate

    let lTime = fabs(interValTime)

    

    let iSeconds = Int(lTime.truncatingRemainder(dividingBy: 60))

    let iMinutes = Int((lTime / 60) / 60)

    let iHours = Int(fabs((lTime / 3600).truncatingRemainder(dividingBy:24)))

    let iDays: Int = Int(lTime / 60 / 60 / 24);

    //    let iMonth = Int(lTime / 60 / 60 / 24 / 12);

    //    let iYears = Int(lTime / 60 / 60 / 24 / 384);

    var timeString = ""

    if (iHours<1 && iMinutes>0)

    {

        timeString = "\(iMinutes)\(locationTextValue("mins", str_cht:"分", str_chs: "分"))"

    }else if (iHours>0&&iDays<1 && iMinutes>0) {

        timeString = "\(iHours)\(locationTextValue("hour", str_cht:"時", str_chs: "時"))\(iMinutes) \(locationTextValue("mins", str_cht:"分", str_chs: "分"))"

    }

    else if (iHours>0&&iDays<1) {

        timeString = "\(iHours)\(locationTextValue("hour", str_cht:"時", str_chs: "时"))"

        

    }else if (iDays>0 && iHours>0)

    {

        timeString = "\(iDays)\(locationTextValue("day", str_cht:"天", str_chs: "天"))\(iHours) \(locationTextValue("hour", str_cht:"時", str_chs: "時"))"

        

    }

    else if (iDays>0)

    {

        timeString = "\(iDays)\(locationTextValue("Day", str_cht:"天", str_chs: "天"))"

        

    } else {

        timeString = "\(iSeconds)\(locationTextValue("seconds", str_cht:"秒", str_chs: "秒"))"

    }

    return timeString

}