iOS：NSOrderedDescending和NSOrderedAscending问题

问题描述

我想比较日期，并使用此代码

I want to compare dates and I use this code

在一个示例中，我的日期的日期值为：
date1 = 6/06/2011
date2 = 8/06/2011

in one example date values for my date are:date1 = 6/06/2011date2 = 8/06/2011

如果dateSelected = 7/06/2011没关系，但是如果dateSelected = 6/06/2011或dateSelected = 8 / 06/2011代码没有在我的如果中输入，为什么？？？

if dateSelected = 7/06/2011 it's all ok, but if dateSelected = 6/06/2011 or dateSelected = 8/06/2011 the code don't entry inside my "if", why???

if (([dateSelected compare:date1] == NSOrderedDescending) &&
                ([dateSelected compare:date2]== NSOrderedAscending))
            {}

推荐答案

NSDates表示自2000年1月1日00:00 UTC开始的时间点。因此，所有这些日期都有时间成分。 -比较：比较日期和时间。

NSDates represent a point in time since 1/1/2000 00:00 UTC. So all of those dates have time components. -compare: compares date and time.

想必您真的想检查所选日期是否在6/6/2011 00:00到9/6/2011 00:00之间。另外，您可能希望日期6/6/2011 00:00计入该范围内。因此，您需要类似

Presumably, you really want to check if the date selected is between 6/6/2011 00:00 and 9/6/2011 00:00. Also you probably want the date 6/6/2011 00:00 to count as in the range. So you need something like

NSComparisonResult compareStart = [date1 compare: selectedDate]; // date1 is 6/6/2011 00:00
NSComparisonResult compareEnd = [date2 compare: selectedDate];   // date2 is 9/6/2011 00:00

if ((compareStart == NSOrderedAscending) || (compareStart == NSOrderedSame)
    && (compareEnd == NSOrderedDescending))
{
    // date is in the right range
}

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