两个NSDates之间的快速日子 [英] Swift days between two NSDates

问题描述

我想知道是否有一些新的和可怕的可能性来获得Swift /新Cocoa中两个NSDates之间的天数？

I'm wondering if there is some new and awesome possibility to get the amount of days between two NSDates in Swift / the "new" Cocoa?

例如。就像在Ruby中我会这样做：

E.g. like in Ruby I would do:

(end_date - start_date).to_i

推荐答案

接受的答案不会在两个日期之间返回正确的日期编号。你也必须考虑时差。例如，如果您比较日期 2015-01-01 10:00 和 2015-01-02 09:00 ，这些日期之间的天数将返回0（零），因为这些日期之间的差异小于24小时（23小时）。

The accepted answer won't return the correct day number between two dates. You have to consider the time difference as well. For example if you compare the dates 2015-01-01 10:00 and 2015-01-02 09:00, days between those dates will return as 0 (zero) since the difference between those dates is less than 24 hours (it's 23 hours).

如果您的目的是为了获得两个日期之间的确切日期数，您可以解决此问题，如下所示：

If your purpose is to get the exact day number between two dates, you can work around this issue like this:

// Assuming that firstDate and secondDate are defined
// ...

let calendar = NSCalendar.currentCalendar()

// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDayForDate(firstDate)
let date2 = calendar.startOfDayForDate(secondDate)

let flags = NSCalendarUnit.Day
let components = calendar.components(flags, fromDate: date1, toDate: date2, options: [])

components.day  // This will return the number of day(s) between dates

Swift 3版本

Swift 3 Version

let calendar = NSCalendar.current

// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: firstDate)
let date2 = calendar.startOfDay(for: secondDate)

let components = calendar.dateComponents([.day], from: date1, to: date2)

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