iOS swift5 Date 日期增加(减少)一天 前一天 后一天

前一天

        //前一天
        let currentDay = datePicker.date
        let lastDay = Date(timeInterval: 24*60*60, since: currentDay)
        datePicker.date = lastDay

后一天

        //后一天
        let currentDay = datePicker.date
        let nextDay = Date(timeInterval: 24*60*60, since: currentDay)
        datePicker.date = nextDay

参考博客：
iOS 日期加一天算法 - csdn