Question

如何以YYYY-MM-DD的格式显示一周前的日期，例如Swift中的这个“2015-02-18”

Answer 1

您可以使用日历date(byAdding component:)计算今天减一周，然后您可以使用DateFormatter根据需要设置日期格式：

let lastWeekDate = Calendar.current.date(byAdding: .weekOfYear, value: -1, to: Date())!
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
dateFormatter.dateFormat = "yyyy-MM-dd"
let lastWeekDateString = dateFormatter.string(from: lastWeekDate)

Answer 2

要以特定格式获取日期，您可以使用NSDateFormatter：

var todaysDate:NSDate = NSDate()
var dateFormatter:NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
var todayString:String = dateFormatter.stringFromDate(todaysDate)

NSDate()返回当前日期

For calculating date you should use calendar

let calendar = NSCalendar.currentCalendar()
let weekAgoDate = calendar.dateByAddingUnitdateByAddingUnit(.WeekOfYearCalendarUnit, value: -1, toDate: NSDate(), options: nil)!
var dateFormatter:NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
var aWeekAgoString:String = dateFormatter.stringFromDate(weekAgoDate)

Answer 3

扩展NSDate是一个坏主意吗？

import UIKit

extension NSDate {

    func previousWeek() -> NSDate {
        return dateByAddingTimeInterval(-7*24*60*60)
    }

    func asString(format:String) -> String {
        var dateFormatter : NSDateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = format
        return dateFormatter.stringFromDate(self)
    }
}

NSDate().previousWeek().asString("yyyy-MM-dd")

Answer 4

斯威夫特3：

        let lastWeekDate = NSCalendar.current.date(byAdding: .weekOfYear, value: -1, to: NSDate() as Date)
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd"
        var aWeekBefore:String = dateFormatter.string(from: lastWeekDate!)

你如何以YYYY-MM-DD格式快速获得上周的约会？

4 个答案: