Swift - 两个时间戳相减后，算剩余时间

    //MARK: -时间戳转时间函数
    func timeStampToString(timeStamp: Int)->String {
        let days = Int(timeStamp/(3600*24))
        let hours = Int((timeStamp - days*24*3600)/3600)
        let minute = Int((timeStamp - days*24*3600-hours*3600)/60)
        let second = timeStamp - days*24*3600-hours*3600-minute*60
        let timeString = String.init(format: "%d天%d小时%d分%d秒", days,hours,minute,second)
        return timeString
    }