NSDateComponents weekOfYear 返回错误的日期 [英] NSDateComponents weekOfYear returns wrong date

问题描述

所以我正在制作一个基本的周选择器，您可以在其中选择周数和年份，并从周开始点获取相应的日期.

so i am making a basic week picker, where you can pick a week number and year, and get the corresponding date from the weeks startpoint.

基本测试场景

let calendar = NSCalendar.currentCalendar()
let components = NSDateComponents()
components.year = 2015
components.weekOfYear = 15
print(calendar.dateFromComponents(components)!)

你可以看到，我将通缉年份设置为 2015 年，通缉周设置为 15，但我得到的结果是:2014-12-31 23:00:00 +0000"

You can see, that i set the wanted year to 2015 and the wanted week to 15, but the result i get is: "2014-12-31 23:00:00 +0000"

...这真的让我很困惑.无论我选择哪一周和哪一年，它都会在 12 月关闭.

... and thats really gets me hanging. No matter what week and year i choose, it will always be off and in december.

预先感谢您的帮助.

推荐答案

weekOfYear 与 yearForWeekOfYear 配合使用:

let calendar = NSCalendar.currentCalendar()
let components = NSDateComponents()

components.yearForWeekOfYear = 2015
components.weekOfYear = 15

print(calendar.dateFromComponents(components)!)
// 2015-04-05 22:00:00 +0000

<小时>

Swift 3 及更高版本的更新:

let calendar = Calendar.current
var components = DateComponents()

components.yearForWeekOfYear = 2015
components.weekOfYear = 15

print(calendar.date(from: components)!)

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