iOS：比较两个NSDate-s没有时间部分 [英] iOS: Compare two NSDate-s without time portion

问题描述

我想比较两个日期：date1和date2

  2011-06-06 12：59：48.994 Project [419 ：707] firstDate：2011-06-06 10:59:21 +0000 
 2011-06-06 12：59：49.004项目[419：707] selectedData：2011-06-06 10:59:17 + 0000 
  

但这些日期有不同的时间，当我使用NSOrderedSame它不工作，我解决了？

我的代码：

  NSDate * firstDate = [appDelegate.project objectAtIndex：i] objectAtIndex：3]; 
 NSDate * secondDate = [[appDelegate.project objectAtIndex：i] objectAtIndex：4]; 
 
 NSCalendar * calendar = [NSCalendar currentCalendar]; 
 NSInteger comps =（NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit）; 
 
 NSDateComponents * date1Components = [日历组件：comps 
 fromDate：firstDate]; 
 NSDateComponents * date2Components = [日历组件：comps 
 fromDate：secondDate]; 
 NSDateComponents * date3Components = [calendar components：comps fromDate：appDelegate.selectedDate]; 
 
 NSLog（@firstDate：％@，[date1Components date]）; 
 NSLog（@secondDate：％@，[date2Components date]）; 
 NSLog（@selectedData：％@，[date3Components date]）; 
 
 NSComparisonResult compareStart = [[date1Components date] compare：[date3Components date]]; 
 NSComparisonResult compareEnd = [[date2Components date] compare：[date3Components date]]; 
 
 if（（compareStart == NSOrderedAscending || compareStart == NSOrderedSame）
&&（compareEnd == NSOrderedDescending || compareEnd == NSOrderedSame））
 
 {
 NSLog（@inside）; 
 

然后我想比较我的日期和条目在if当date1< = selectedDate< = = date2;现在我明白，因为我有一个警告：我应该添加这个[date1Components date]，它的工作;问题是我在NSLog的空值，为什么

解决方案

  NSCalendar * calendar = [NSCalendar currentCalendar]; 
 NSInteger comps =（NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit）; 
 
 NSDateComponents * date1Components = [日历组件：comps 
 fromDate：date1]; 
 NSDateComponents * date2Components = [日历组件：comps 
 fromDate：date2]; 
 
 date1 = [calendar dateFromComponents：date1Components]; 
 date2 = [calendar dateFromComponents：date2Components]; 
 
 NSComparisonResult result = [date1 compare：date2]; 
 if（result == NSOrderedAscending）{
} else if（result == NSOrderedDescending）{
} else {
 //相同
} 
 





---

还有一种方便的方法来为给定日期创建日期表示给定单元的开头： [aCalendar rangeOfUnit：startDate：interval：forDate：]

要说明此方法的工作原理，请参阅此代码，

  NSDate * now = [NSDate日期]; 
 NSDate * startOfToday = nil; 
 NSDate * startOfThisWeek = nil; 
 NSDate * startOfThisMonth = nil; 
 NSDate * startOfThisYear = nil; 
 [[NSCalendar currentCalendar] rangeOfUnit：NSDayCalendarUnit startDate：& startOfToday interval：NULL forDate：now]; 
 [[NSCalendar currentCalendar] rangeOfUnit：NSWeekCalendarUnit startDate：& startOfThisWeek interval：NULL forDate：now]; 
 [[NSCalendar currentCalendar] rangeOfUnit：NSMonthCalendarUnit startDate：& startOfThisMonth interval：NULL forDate：now]; 
 [[NSCalendar currentCalendar] rangeOfUnit：NSYearCalendarUnit startDate：& startOfThisYear interval：NULL forDate：now]; 
 
 NSDateFormatter * formatter = [[NSDateFormatter alloc] init]; 
 [formatter setDateStyle：NSDateFormatterFullStyle]; 
 [formatter setTimeStyle：NSDateFormatterFullStyle]; 
 
 NSLog（@％@，[formatter stringFromDate：now]）; 
 NSLog（@％@，[formatter stringFromDate：startOfToday]）; 
 NSLog（@％@，[formatter stringFromDate：startOfThisWeek]）; 
 NSLog（@％@，[formatter stringFromDate：startOfThisMonth]）; 
 NSLog（@％@，[formatter stringFromDate：startOfThisYear]）; 
  

结果：

 code> 2012年7月12日星期四下午4:36:07中欧夏令时间
 2012年7月12日星期四中午12:00:00中欧夏令时间
 7月7日星期日8，2012，12:00:00中欧夏令时
 2012年7月1日星期日，中午12:00:00中欧夏令时
 2012年1月1日星期日12:00： 00 AM中欧标准时间
  

这样我们可以将第一个代码缩短为：

  [[NSCalendar currentCalendar] rangeOfUnit：NSDayCalendarUnit startDate：& date1 interval：NULL forDate：date1] 
 [[NSCalendar currentCalendar] rangeOfUnit：NSDayCalendarUnit startDate：& date2 interval：NULL forDate：date2]; 
 
 NSComparisonResult result = [date1 compare：date2]; 
 if（result == NSOrderedAscending）{
} else if（result == NSOrderedDescending）{
} else {
 //相同
} 
  

请注意，在此代码中， date1 和 date2 将被覆盖。或者，您可以传递对 startDate 的另一个NSDate指针的引用，如上面的代码所示，其中 now 保持不变。

I want to compare two dates: date1 and date2

2011-06-06 12:59:48.994 Project[419:707] firstDate:2011-06-06 10:59:21 +0000
2011-06-06 12:59:49.004 Project[419:707] selectedData:2011-06-06 10:59:17 +0000

but these dates have different time and when I use NSOrderedSame it don't work fine, how can I solve?

my code:

NSDate *firstDate = [[appDelegate.project objectAtIndex:i]objectAtIndex:3];
NSDate *secondDate = [[appDelegate.project objectAtIndex:i]objectAtIndex:4];

NSCalendar *calendar = [NSCalendar currentCalendar];
NSInteger comps = (NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit);

NSDateComponents *date1Components = [calendar components:comps 
                                                            fromDate:firstDate];
NSDateComponents *date2Components = [calendar components:comps 
                                                            fromDate:secondDate];
NSDateComponents *date3Components = [calendar components:comps fromDate:appDelegate.selectedDate];

NSLog(@"firstDate:%@", [date1Components date]);
NSLog(@"secondDate:%@", [date2Components date]);
NSLog(@"selectedData:%@", [date3Components date]);

NSComparisonResult compareStart = [[date1Components date] compare: [date3Components date]]; 
NSComparisonResult compareEnd = [[date2Components date] compare: [date3Components date]]; 

if ((compareStart == NSOrderedAscending || compareStart == NSOrderedSame)
     && (compareEnd == NSOrderedDescending || compareEnd == NSOrderedSame))

{
    NSLog(@"inside");

Then I want to compare my dates and entry inside the "if" when date1 <= selectedDate <= date2; now I understand because I have a warning: I should add this "[date1Components date]" and it work; the problem is that I have in the NSLog null values, why??

解决方案

NSCalendar *calendar = [NSCalendar currentCalendar];
NSInteger comps = (NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit);

NSDateComponents *date1Components = [calendar components:comps 
                                                fromDate: date1];
NSDateComponents *date2Components = [calendar components:comps 
                                                fromDate: date2];

date1 = [calendar dateFromComponents:date1Components];
date2 = [calendar dateFromComponents:date2Components];

NSComparisonResult result = [date1 compare:date2];
if (result == NSOrderedAscending) {
} else if (result == NSOrderedDescending) {
}  else {
    //the same
}

---

There is another handy method to create for a given date the date that represents the start of a given unit: [aCalendar rangeOfUnit:startDate:interval:forDate:]
To illustrate how this method works, see this code, that easily creates the date for the beginning of the day, week, month and year for a given date (here: now).

NSDate *now = [NSDate date];
NSDate *startOfToday = nil;
NSDate *startOfThisWeek = nil;
NSDate *startOfThisMonth = nil;
NSDate *startOfThisYear = nil;
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&startOfToday interval:NULL forDate:now];
[[NSCalendar currentCalendar] rangeOfUnit:NSWeekCalendarUnit startDate:&startOfThisWeek interval:NULL forDate:now];
[[NSCalendar currentCalendar] rangeOfUnit:NSMonthCalendarUnit startDate:&startOfThisMonth interval:NULL forDate:now];
[[NSCalendar currentCalendar] rangeOfUnit:NSYearCalendarUnit startDate:&startOfThisYear interval:NULL forDate:now];

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateStyle:NSDateFormatterFullStyle];
[formatter setTimeStyle:NSDateFormatterFullStyle];

NSLog(@"%@", [formatter stringFromDate:now]);
NSLog(@"%@", [formatter stringFromDate:startOfToday]);
NSLog(@"%@", [formatter stringFromDate:startOfThisWeek]);
NSLog(@"%@", [formatter stringFromDate:startOfThisMonth]);
NSLog(@"%@", [formatter stringFromDate:startOfThisYear]);

result:

Thursday, July 12, 2012, 4:36:07 PM Central European Summer Time 
Thursday, July 12, 2012, 12:00:00 AM Central European Summer Time 
Sunday, July 8, 2012, 12:00:00 AM Central European Summer Time 
Sunday, July 1, 2012, 12:00:00 AM Central European Summer Time 
Sunday, January 1, 2012, 12:00:00 AM Central European Standard Time

this allows us to shorten the first code to:

[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&date1 interval:NULL forDate:date1];
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&date2 interval:NULL forDate:date2];

NSComparisonResult result = [date1 compare:date2];
if (result == NSOrderedAscending) {
} else if (result == NSOrderedDescending) {
}  else {
    //the same
}

Note, that in this code, date1 and date2 will be overwritten. Alternatively you can pass in a reference to another NSDate pointer for startDate as shown in the code above, where now stays untouched.

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