Time a go in words for swift

TimeAgoInWords.swift

extension NSDate {

  func timeAgoInWords() -> String {
    let secondsDiff = self.timeIntervalSinceNow
    if secondsDiff < 60 {
      return "JUST_NOW".localized
    }
    if secondsDiff < 3600 {
      let minutesAgo = secondsDiff / 60
      return "X_MINS_AGO".localizedStringWithVariables(minutesAgo)
    }
    if secondsDiff < 3600*24 {
      let hoursAgo = floor(secondsDiff / 3600)
      return "X_HOURS_AGO".localizedStringWithVariables(hoursAgo)
    }
    else {
      let hoursAgo = floor(secondsDiff / (3600*24))
      return "X_DAYS_AGO".localizedStringWithVariables(hoursAgo)
    }
  }
  
}