blocks|key|1320001|text|您还可以检查日期和当前日期之间的时间间隔：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1320002|[myDate+timeIntervalSinceNow]|code-block|syntax|javascript|1320003|这将提供myDate和当前日期/时间之间的时间间隔(以秒为单位)。|1320004|Link。|offset|length|1320005|编辑:每个人请注意:我很清楚myDate+timeIntervalSinceNow并不能明确地决定myDate是否是今天的版本。|1320006|我将这个答案留在原处，这样如果有人正在寻找类似的东西，并且myDate+timeIntervalSinceNow很有用，他们可能会在这里找到它。|1320007|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDate/timeIntervalSinceNow^0|0|0|0|0|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|11|8|@]|9|@$K|12|L|13|1|14]]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

You could also check the time interval between the date you have, and the current date:

<pre><code>[myDate timeIntervalSinceNow]
</code></pre>

This will give you the time interval, in seconds, between myDate and the current date/time.

<a href="http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDate/timeIntervalSinceNow" rel="nofollow noreferrer">Link</a>.

Edit: Note to everyone: I'm well aware that [myDate timeIntervalSinceNow] does not unambiguously determine whether myDate is today.

I am leaving this answer as is so that if someone is looking for something similar and [myDate timeIntervalSinceNow] is useful, they may find it here.

blocks|key|1320075|text|我会尝试将今天的日期标准化为午夜，将第二个日期标准化为午夜，然后比较是否为相同的NSDate。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1320076|在an+Apple+example中，这里是如何将今天的日期归一化到午夜，对第二个日期执行相同的操作并进行比较：|offset|length|1320077|NSCalendar+*+gregorian+=+[[NSCalendar+alloc]
+++++++++++++++++++++++++++++++initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents+*+components+=
++++[gregorian+components:
+++++++++++++++++(NSYearCalendarUnit%7CNSMonthCalendarUnit%7CNSDayCalendarUnit)
+++++++++++++++++fromDate:[NSDate+date]];
NSDate+*+today+=+[gregorian+dateFromComponents:components];|code-block|syntax|javascript|1320078|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/DatesAndTimes/Articles/dtCalendricalCalculations.html#//apple_ref/doc/uid/TP40007836^0|0|1|G|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

I would try to get today's date normalized to midnight and the second date, normalize to midnight then compare if it is the same NSDate.

From <a href="http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/DatesAndTimes/Articles/dtCalendricalCalculations.html#//apple_ref/doc/uid/TP40007836" rel="noreferrer">an Apple example</a> here's how you normalize to midnight today's date, do the same for the second date and compare:

<pre><code>NSCalendar * gregorian = [[NSCalendar alloc]
 initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents * components =
 [gregorian components:
 (NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit)
 fromDate:[NSDate date]];
NSDate * today = [gregorian dateFromComponents:components];
</code></pre>

blocks|key|1320122|text|这可能会被修改为一个NSDate类别，但我使用了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1320123|//+Seconds+per+day+(24h+*+60m+*+60s)
#define+kSecondsPerDay+86400.0f

%2B+(BOOL)+dateIsToday:(NSDate*)dateToCheck
{
++++//+Split+today+into+components
++++NSCalendar*+gregorian+=+[[NSCalendar+alloc]+initWithCalendarIdentifier:NSGregorianCalendar];
++++NSDateComponents*+comps+=+[gregorian+components:(NSYearCalendarUnit%7CNSMonthCalendarUnit%7CNSDayCalendarUnit%7CNSHourCalendarUnit%7CNSMinuteCalendarUnit%7CNSSecondCalendarUnit)+
++++++++++++++++++++++++++++++++++++++++fromDate:[NSDate+date]];

++++//+Set+to+this+morning+00:00:00
++++[comps+setHour:0];
++++[comps+setMinute:0];
++++[comps+setSecond:0];
++++NSDate*+theMidnightHour+=+[gregorian+dateFromComponents:comps];
++++[gregorian+release];

++++//+Get+time+difference+(in+seconds)+between+date+and+then
++++NSTimeInterval+diff+=+[dateToCheck+timeIntervalSinceDate:theMidnightHour];
++++return+(+diff>=0.0f+&&+diff<kSecondsPerDay+);
}|code-block|syntax|javascript|1320124|(但是，将两个日期字符串与原始问题中的日期字符串进行比较几乎会让人感觉“更干净”。)|1320125|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This could probably be reworked as an NSDate category, but i used:

<pre><code>// Seconds per day (24h * 60m * 60s)
#define kSecondsPerDay 86400.0f

+ (BOOL) dateIsToday:(NSDate*)dateToCheck
{
 // Split today into components
 NSCalendar* gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
 NSDateComponents* comps = [gregorian components:(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit) 
 fromDate:[NSDate date]];

 // Set to this morning 00:00:00
 [comps setHour:0];
 [comps setMinute:0];
 [comps setSecond:0];
 NSDate* theMidnightHour = [gregorian dateFromComponents:comps];
 [gregorian release];

 // Get time difference (in seconds) between date and then
 NSTimeInterval diff = [dateToCheck timeIntervalSinceDate:theMidnightHour];
 return ( diff&gt;=0.0f &amp;&amp; diff&lt;kSecondsPerDay );
}
</code></pre>

(However, comparing the two date strings as in the original question almost feels 'cleaner'..)

blocks|key|1105205|text|NSDate+*dateOne+=+yourDate;
NSDate+*dateTwo+=+[NSDate+date];++

switch+([dateOne+compare:dateTwo])
{++
++++case+NSOrderedAscending:++
++++++++NSLog(@”NSOrderedAscending”);++
++++++++break;++

++++case+NSOrderedSame:+
++++++++NSLog(@”NSOrderedSame”);++
++++++++break;

++++case+NSOrderedDescending:++
++++++++NSLog(@”NSOrderedDescending”);++
++++++++break;++
}++|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1105206|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>NSDate *dateOne = yourDate;
NSDate *dateTwo = [NSDate date]; 

switch ([dateOne compare:dateTwo])
{ 
 case NSOrderedAscending: 
 NSLog(@”NSOrderedAscending”); 
 break; 

 case NSOrderedSame: 
 NSLog(@”NSOrderedSame”); 
 break;

 case NSOrderedDescending: 
 NSLog(@”NSOrderedDescending”); 
 break; 
} 
</code></pre>

blocks|key|1320196|text|这是您的问题的一个分支，但是如果您想打印带有“今天”或“昨天”的NSDate，请使用函数|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1320197|-+(void)setDoesRelativeDateFormatting:(BOOL)b|code-block|syntax|javascript|1320198|对于NSDateFormatter|1320199|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This is an offshoot to your question, but if you want to print an NSDate with "Today" or "Yesterday", use the function

<pre><code>- (void)setDoesRelativeDateFormatting:(BOOL)b
</code></pre>

for NSDateFormatter

blocks|key|1320250|text|如果您有很多这样的日期比较，那么对calendar:components:fromDate的调用就会占用很多时间。根据我做过的一些分析，它们似乎相当昂贵。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1320251|假设您正在尝试确定某个日期数组中的哪个日期(例如NSArray+*datesToCompare+)与某个给定日期(例如NSDate+*baseDate+)是同一天，那么您可以使用类似以下内容(部分改编自上面的答案)：|1320252|NSDate+*baseDate+=+[NSDate+date];

NSArray+*datesToCompare+=+[NSArray+arrayWithObjects:[NSDate+date],+
+++++++++++++++++++++++++++[NSDate+dateWithTimeIntervalSinceNow:100],
+++++++++++++++++++++++++++[NSDate+dateWithTimeIntervalSinceNow:1000],
+++++++++++++++++++++++++++[NSDate+dateWithTimeIntervalSinceNow:-10000],
+++++++++++++++++++++++++++[NSDate+dateWithTimeIntervalSinceNow:100000],
+++++++++++++++++++++++++++[NSDate+dateWithTimeIntervalSinceNow:1000000],
+++++++++++++++++++++++++++[NSDate+dateWithTimeIntervalSinceNow:50],
+++++++++++++++++++++++++++nil];

//+determine+the+NSDate+for+midnight+of+the+base+date:
NSCalendar*+calendar+=+[NSCalendar+currentCalendar];
NSDateComponents*+comps+=+[calendar+components:(NSYearCalendarUnit%7CNSMonthCalendarUnit%7CNSDayCalendarUnit)+
+++++++++++++++++++++++++++++++++++++++fromDate:baseDate];
NSDate*+theMidnightHour+=+[calendar+dateFromComponents:comps];

//+set+up+a+localized+date+formatter+so+we+can+see+the+answers+are+right!
NSDateFormatter+*dateFormatter+=+[[NSDateFormatter+alloc]+init];
[dateFormatter+setDateStyle:NSDateFormatterMediumStyle];
[dateFormatter+setTimeStyle:NSDateFormatterMediumStyle];

//+determine+which+dates+in+an+array+are+on+the+same+day+as+the+base+date:
for+(NSDate+*date+in+datesToCompare)+{
++++NSTimeInterval+interval+=+[date+timeIntervalSinceDate:theMidnightHour];
++++if+(interval+>=+0+&&+interval+<+60*60*24)+{
++++++++NSLog(@"%25@+is+on+the+same+day+as+%25@",+[dateFormatter+stringFromDate:date],+[dateFormatter+stringFromDate:baseDate]);
++++}
++++else+{
++++++++NSLog(@"%25@+is+NOT+on+the+same+day+as+%25@",+[dateFormatter+stringFromDate:date],+[dateFormatter+stringFromDate:baseDate]);
++++}
}|code-block|syntax|javascript|1320253|输出：|1320254|Nov+23,+2011+1:32:00+PM+is+on+the+same+day+as+Nov+23,+2011+1:32:00+PM
Nov+23,+2011+1:33:40+PM+is+on+the+same+day+as+Nov+23,+2011+1:32:00+PM
Nov+23,+2011+1:48:40+PM+is+on+the+same+day+as+Nov+23,+2011+1:32:00+PM
Nov+23,+2011+10:45:20+AM+is+on+the+same+day+as+Nov+23,+2011+1:32:00+PM
Nov+24,+2011+5:18:40+PM+is+NOT+on+the+same+day+as+Nov+23,+2011+1:32:00+PM
Dec+5,+2011+3:18:40+AM+is+NOT+on+the+same+day+as+Nov+23,+2011+1:32:00+PM
Nov+23,+2011+1:32:50+PM+is+on+the+same+day+as+Nov+23,+2011+1:32:00+PM|1320255|entityMap^0|H|S|0|O|N|1N|G|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

If you have a lot of these date comparisons, then the calls to <code>calendar:components:fromDate</code> start to take up a lot of time. According to some profiling I have done, they seem to be quite expensive.

Say you are trying to determine which from some array of dates, say <code>NSArray *datesToCompare</code>, are the same day as some given day, say <code>NSDate *baseDate</code>, then you can use something like the following (partly adapted from an answer above):

<pre><code>NSDate *baseDate = [NSDate date];

NSArray *datesToCompare = [NSArray arrayWithObjects:[NSDate date], 
 [NSDate dateWithTimeIntervalSinceNow:100],
 [NSDate dateWithTimeIntervalSinceNow:1000],
 [NSDate dateWithTimeIntervalSinceNow:-10000],
 [NSDate dateWithTimeIntervalSinceNow:100000],
 [NSDate dateWithTimeIntervalSinceNow:1000000],
 [NSDate dateWithTimeIntervalSinceNow:50],
 nil];

// determine the NSDate for midnight of the base date:
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDateComponents* comps = [calendar components:(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit) 
 fromDate:baseDate];
NSDate* theMidnightHour = [calendar dateFromComponents:comps];

// set up a localized date formatter so we can see the answers are right!
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
[dateFormatter setTimeStyle:NSDateFormatterMediumStyle];

// determine which dates in an array are on the same day as the base date:
for (NSDate *date in datesToCompare) {
 NSTimeInterval interval = [date timeIntervalSinceDate:theMidnightHour];
 if (interval &gt;= 0 &amp;&amp; interval &lt; 60*60*24) {
 NSLog(@"%@ is on the same day as %@", [dateFormatter stringFromDate:date], [dateFormatter stringFromDate:baseDate]);
 }
 else {
 NSLog(@"%@ is NOT on the same day as %@", [dateFormatter stringFromDate:date], [dateFormatter stringFromDate:baseDate]);
 }
}
</code></pre>

Output:

<pre><code>Nov 23, 2011 1:32:00 PM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 1:33:40 PM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 1:48:40 PM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 10:45:20 AM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 24, 2011 5:18:40 PM is NOT on the same day as Nov 23, 2011 1:32:00 PM
Dec 5, 2011 3:18:40 AM is NOT on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 1:32:50 PM is on the same day as Nov 23, 2011 1:32:00 PM
</code></pre>

blocks|key|1105360|text|我的解决方案是通过除法计算自1970年以来经过了多少天，并比较整数部分|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105361|#define+kOneDay+(60*60*24)
-+(BOOL)isToday+{
++NSInteger+offset+=+[[NSTimeZone+defaultTimeZone]+secondsFromGMT];

++NSInteger+days+=[self+timeIntervalSince1970]+%2B+offset;
++NSInteger+currentDays+=+[[NSDate+date]+timeIntervalSince1970]+%2B+offset;
++return+(days+/+kOneDay+==+currentDays+/+kOneDay);
}|code-block|syntax|javascript|1105362|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

My solution is calculate how much days passed since 1970 by division and compare the integer part

<pre><code>#define kOneDay (60*60*24)
- (BOOL)isToday {
 NSInteger offset = [[NSTimeZone defaultTimeZone] secondsFromGMT];

 NSInteger days =[self timeIntervalSince1970] + offset;
 NSInteger currentDays = [[NSDate date] timeIntervalSince1970] + offset;
 return (days / kOneDay == currentDays / kOneDay);
}
</code></pre>

blocks|key|1105417|text|请参阅苹果公司的文档条目，标题为“执行日历计算”[link]。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1105418|该页面上的清单13建议您使用以下命令来确定两天之间的午夜次数：|1105419|-+(NSInteger)midnightsFromDate:(NSDate+*)startDate+toDate:(NSDate+*)endDate
{
++++NSCalendar+*calendar+=+[NSCalendar+autoupdatingCurrentCalendar];
++++NSInteger+startDay+=+[calendar+ordinalityOfUnit:NSDayCalendarUnit
+++++++++++++++++++++++++++++++++++++++++++++inUnit:NSEraCalendarUnit
++++++++++++++++++++++++++++++++++++++++++++forDate:startDate];
++++NSInteger+endDay+=+[calendar+ordinalityOfUnit:NSDayCalendarUnit
+++++++++++++++++++++++++++++++++++++++++++inUnit:NSEraCalendarUnit
++++++++++++++++++++++++++++++++++++++++++forDate:endDate];
++++return+endDay+-+startDay;
}|code-block|syntax|javascript|1105420|然后，您可以通过使用该方法并查看它是否返回0来确定两天是否相同。|1105421|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/DatesAndTimes/Articles/dtCalendricalCalculations.html^0|O|6|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|6|7|Y|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|Z|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Refer to Apple's documentation entry entitled "Performing Calendar Calculations" <a href="http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/DatesAndTimes/Articles/dtCalendricalCalculations.html" rel="noreferrer">[link]</a>.

Listing 13 on that page suggests that to determine the number of midnights between days, you use:

<pre><code>- (NSInteger)midnightsFromDate:(NSDate *)startDate toDate:(NSDate *)endDate
{
 NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
 NSInteger startDay = [calendar ordinalityOfUnit:NSDayCalendarUnit
 inUnit:NSEraCalendarUnit
 forDate:startDate];
 NSInteger endDay = [calendar ordinalityOfUnit:NSDayCalendarUnit
 inUnit:NSEraCalendarUnit
 forDate:endDate];
 return endDay - startDay;
}
</code></pre>

You may then determine if two days are the same by using that method and seeing if it returns 0 or not.

blocks|key|1105448|text|不需要纠结于组件、era和其他东西。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105449|NSCalendar提供了一种方法，用于获取现有日期的某个时间单位的开始时间。|1105450|此代码将获取今天的开始日期和另一个日期，并对其进行比较。如果它的计算结果为NSOrderedSame，则两个日期都在同一天--今天也是如此。|offset|length|style|CODE|1105451|NSDate+*today+=+nil;
NSDate+*beginningOfOtherDate+=+nil;

NSDate+*now+=+[NSDate+date];
[[NSCalendar+currentCalendar]+rangeOfUnit:NSDayCalendarUnit+startDate:&today+interval:NULL+forDate:now];
[[NSCalendar+currentCalendar]+rangeOfUnit:NSDayCalendarUnit+startDate:&beginningOfOtherDate+interval:NULL+forDate:beginningOfOtherDate];

if([today+compare:beginningOfOtherDate]+==+NSOrderedSame)+{
++++//otherDate+is+a+date+in+the+current+day
}|code-block|syntax|javascript|1105452|entityMap^0|0|0|11|D|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|S|8|@$F|T|G|U|H|I]]|9|@]|A|$]]|$1|J|3|K|5|L|7|V|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

No need to juggle with components, eras and stuff. 

NSCalendar provides an method to get the beginning of a certain time unit for an existing date.

This code will get the begin of today and another date and compare that. If it evaluates to <code>NSOrderedSame</code>, both dates are during the same day — so today.

<pre><code>NSDate *today = nil;
NSDate *beginningOfOtherDate = nil;

NSDate *now = [NSDate date];
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&amp;today interval:NULL forDate:now];
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&amp;beginningOfOtherDate interval:NULL forDate:beginningOfOtherDate];

if([today compare:beginningOfOtherDate] == NSOrderedSame) {
 //otherDate is a date in the current day
}
</code></pre>

blocks|key|1105507|text|对于iOS7和更早版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105508|//this+is+now+=>+need+that+for+the+current+date
NSDate+*+now+=+[NSDate+date];

NSCalendar+*calendar+=+[[NSCalendar+alloc]+initWithCalendarIdentifier:NSGregorianCalendar];
[calendar+setTimeZone:[NSTimeZone+systemTimeZone]];

NSDateComponents+*+components+=+[calendar+components:(+NSYearCalendarUnit%7C++++NSMonthCalendarUnit+%7C+NSDayCalendarUnit+%7C+NSHourCalendarUnit+%7C+NSMinuteCalendarUnit+%7C+NSSecondCalendarUnit)+fromDate:+now];

[components+setMinute:0];
[components+setHour:0];
[components+setSecond:0];

//this+is+Today's+Midnight
NSDate+*todaysMidnight+=+[calendar+dateFromComponents:+components];



//now+timeIntervals+since+Midnight+=>+in+seconds
NSTimeInterval+todayTimeInterval+=+[now+timeIntervalSinceDate:+todaysMidnight];

//now+timeIntervals+since+OtherDate+=>+in+seconds
NSTimeInterval+otherDateTimeInterval+=+[now+timeIntervalSinceDate:+otherDate];

if(otherDateTimeInterval+>+todayTimeInterval)+//otherDate+is+not+in+today
{
++++if((otherDateTimeInterval+-+todayTimeInterval)+<=+86400)+//86400+==+a+day+total+seconds
++++{
++++++++@"yesterday";
++++}
++++else
++++{
++++++++@"earlier";
++++}
}
else
{
++++@"today";
}


now+=+nil;
calendar+=+nil;
components+=+nil;
todaysMidnight+=+nil;

NSLog("Thank+you+:-)");|code-block|syntax|javascript|1105509|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

for iOS7 and earlier:

<pre><code>//this is now =&gt; need that for the current date
NSDate * now = [NSDate date];

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setTimeZone:[NSTimeZone systemTimeZone]];

NSDateComponents * components = [calendar components:( NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate: now];

[components setMinute:0];
[components setHour:0];
[components setSecond:0];

//this is Today's Midnight
NSDate *todaysMidnight = [calendar dateFromComponents: components];



//now timeIntervals since Midnight =&gt; in seconds
NSTimeInterval todayTimeInterval = [now timeIntervalSinceDate: todaysMidnight];

//now timeIntervals since OtherDate =&gt; in seconds
NSTimeInterval otherDateTimeInterval = [now timeIntervalSinceDate: otherDate];

if(otherDateTimeInterval &gt; todayTimeInterval) //otherDate is not in today
{
 if((otherDateTimeInterval - todayTimeInterval) &lt;= 86400) //86400 == a day total seconds
 {
 @"yesterday";
 }
 else
 {
 @"earlier";
 }
}
else
{
 @"today";
}


now = nil;
calendar = nil;
components = nil;
todaysMidnight = nil;

NSLog("Thank you :-)");
</code></pre>

blocks|key|1105531|text|看看我们的Erica+Sadun的伟大的NSDate+extension。使用起来非常简单。在这里进行优化：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1105532|http://github.com/erica/NSDate-Extensions|1105533|它已经在这篇文章中出现了：https://stackoverflow.com/a/4052798/362310|1105534|entityMap|0|LINK|mutability|MUTABLE|url|1|https://stackoverflow.com/a/4052798/362310^0|K|G|0|0|15|0|0|D|16|1|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|H|3|I|5|6|7|Z|8|@]|D|@$9|10|A|11|1|12]]|E|$]]|$1|J|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|G]]|Q|$5|M|N|O|E|$P|R]]]]

Check our Erica Sadun's great <code>NSDate extension</code>. Very simple to use. Fine it here:

<a href="http://github.com/erica/NSDate-Extensions" rel="nofollow noreferrer">http://github.com/erica/NSDate-Extensions</a>

It's already there in this post: <a href="https://stackoverflow.com/a/4052798/362310">https://stackoverflow.com/a/4052798/362310</a>

blocks|key|1320535|text|最佳答案的Swift版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1320536|let+cal+=+NSCalendar.currentCalendar()
var+components+=+cal.components([.Era,+.Year,+.Month,+.Day],+fromDate:NSDate())
let+today+=+cal.dateFromComponents(components)!

components+=+cal.components([.Era,+.Year,+.Month,+.Day],+fromDate:aDate);
let+otherDate+=+cal.dateFromComponents(components)!

if(today.isEqualToDate(otherDate))+{
++++//do+stuff
}|code-block|syntax|javascript|1320537|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Swift version of the best answer:

<pre><code>let cal = NSCalendar.currentCalendar()
var components = cal.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
let today = cal.dateFromComponents(components)!

components = cal.components([.Era, .Year, .Month, .Day], fromDate:aDate);
let otherDate = cal.dateFromComponents(components)!

if(today.isEqualToDate(otherDate)) {
 //do stuff
}
</code></pre>

blocks|key|1105613|text|这是我的2美分答案，基于公认的答案，但也支持较新的API。注:我使用公历，因为大多数时间戳都是GMT，但您可以根据需要更改您的时间戳|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105614|func+isDateToday(date:+NSDate)+->+Bool+{
++++let+calendar+=+NSCalendar(calendarIdentifier:+NSCalendarIdentifierGregorian)!
++++if+calendar.respondsToSelector("isDateInToday:")+{
++++++++return+calendar.isDateInToday(date)
++++}
++++let+dateComponents+=+NSCalendarUnit.CalendarUnitYear+%7C+NSCalendarUnit.CalendarUnitMonth+%7C+NSCalendarUnit.CalendarUnitDay
++++let+today+=+calendar.dateFromComponents(calendar.components(dateComponents,+fromDate:+NSDate()))!
++++let+dateToCompare+=+calendar.dateFromComponents(calendar.components(dateComponents,+fromDate:+date))!

++++return+dateToCompare+==+today
}|code-block|syntax|javascript|1105615|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here's my 2 cent answer building on the accepted answer but supporting the newer API as well. Note: I use the Gregorian calendar as most time stamps are GMT but change yours as you see fit

<pre><code>func isDateToday(date: NSDate) -&gt; Bool {
 let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
 if calendar.respondsToSelector("isDateInToday:") {
 return calendar.isDateInToday(date)
 }
 let dateComponents = NSCalendarUnit.CalendarUnitYear | NSCalendarUnit.CalendarUnitMonth | NSCalendarUnit.CalendarUnitDay
 let today = calendar.dateFromComponents(calendar.components(dateComponents, fromDate: NSDate()))!
 let dateToCompare = calendar.dateFromComponents(calendar.components(dateComponents, fromDate: date))!

 return dateToCompare == today
}
</code></pre>

blocks|key|1105638|text|基于最佳答案的Swift扩展：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105639|extension+NSDate+{
++++func+isToday()+->+Bool+{
++++++++let+cal+=+NSCalendar.currentCalendar()
++++++++if+cal.respondsToSelector("isDateInToday:")+{
++++++++++++return+cal.isDateInToday(self)
++++++++}
++++++++var+components+=+cal.components((.CalendarUnitEra+%7C+.CalendarUnitYear+%7C+.CalendarUnitMonth+%7C+.CalendarUnitDay),+fromDate:NSDate())
++++++++let+today+=+cal.dateFromComponents(components)!

++++++++components+=+cal.components((.CalendarUnitEra+%7C+.CalendarUnitYear+%7C+.CalendarUnitMonth+%7C+.CalendarUnitDay),+fromDate:self);
++++++++let+otherDate+=+cal.dateFromComponents(components)!
++++++++return+today.isEqualToDate(otherDate)
++++}
}|code-block|syntax|javascript|1105640|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Swift Extension based on the best answers:

<pre><code>extension NSDate {
 func isToday() -&gt; Bool {
 let cal = NSCalendar.currentCalendar()
 if cal.respondsToSelector("isDateInToday:") {
 return cal.isDateInToday(self)
 }
 var components = cal.components((.CalendarUnitEra | .CalendarUnitYear | .CalendarUnitMonth | .CalendarUnitDay), fromDate:NSDate())
 let today = cal.dateFromComponents(components)!

 components = cal.components((.CalendarUnitEra | .CalendarUnitYear | .CalendarUnitMonth | .CalendarUnitDay), fromDate:self);
 let otherDate = cal.dateFromComponents(components)!
 return today.isEqualToDate(otherDate)
 }
}
</code></pre>

blocks|key|1105680|text|extension+NSDate+{
++func+isToday()+->+Bool+{
++++let+cal+=+NSCalendar.currentCalendar()
++++var+components+=+cal.components([.Era,+.Year,+.Month,+.Day],+fromDate:NSDate())
++++let+today+=+cal.dateFromComponents(components)!

++++components+=+cal.components([.Era,+.Year,+.Month,+.Day],+fromDate:self)
++++let+otherDate+=+cal.dateFromComponents(components)!

++++return+today.isEqualToDate(otherDate)
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1105681|在Swift+2.0上为我工作|unstyled|1105682|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>extension NSDate {
 func isToday() -&gt; Bool {
 let cal = NSCalendar.currentCalendar()
 var components = cal.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
 let today = cal.dateFromComponents(components)!

 components = cal.components([.Era, .Year, .Month, .Day], fromDate:self)
 let otherDate = cal.dateFromComponents(components)!

 return today.isEqualToDate(otherDate)
}
</code></pre>

Worked for me on Swift 2.0

blocks|key|1105741|text|在Swift+2.2和iOS+8之前，无需强制解包的正确和安全的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105742|func+isToday()+->+Bool+{
++++let+calendar+=+NSCalendar.currentCalendar()
++++if+#available(iOS+8.0,+*)+{
++++++++return+calendar.isDateInToday(self)
++++}

++++let+todayComponents+=+calendar.components([.Era,+.Year,+.Month,+.Day],+fromDate:NSDate())
++++let+dayComponents+=+calendar.components([.Era,+.Year,+.Month,+.Day],+fromDate:self)

++++guard+let+today+=+calendar.dateFromComponents(todayComponents),
++++++++day+=+calendar.dateFromComponents(dayComponents)+else+{
++++++++return+false
++++}

++++return+today.compare(day)+==+.OrderedSame
}|code-block|syntax|javascript|1105743|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The correct and safe solution without force-unwrapping, working on Swift 2.2 and before iOS 8:

<pre><code>func isToday() -&gt; Bool {
 let calendar = NSCalendar.currentCalendar()
 if #available(iOS 8.0, *) {
 return calendar.isDateInToday(self)
 }

 let todayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
 let dayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate:self)

 guard let today = calendar.dateFromComponents(todayComponents),
 day = calendar.dateFromComponents(dayComponents) else {
 return false
 }

 return today.compare(day) == .OrderedSame
}
</code></pre>

blocks|key|1105774|text|有一种比上面的许多答案更简单的方法！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105775|NSDate+*date+=+...+//+The+date+you+wish+to+test
NSCalendar+*calendar+=+[NSCalendar+currentCalendar];

if([calendar+isDateInToday:date])+{
++++//do+stuff
}|code-block|syntax|javascript|1105776|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

There is an easier way than many of the above answers! 

<pre><code>NSDate *date = ... // The date you wish to test
NSCalendar *calendar = [NSCalendar currentCalendar];

if([calendar isDateInToday:date]) {
 //do stuff
}
</code></pre>

How to check if an <code>NSDate</code> belongs to today?

I used to check it using first 10 characters from <code>[aDate description]</code>. <code>[[aDate description] substringToIndex:10]</code> returns string like <code>"YYYY-MM-DD"</code> so I compared the string with the string returned by <code>[[[NSDate date] description] substringToIndex:10]</code>.

Is there more fast and/or neat way to check?

Thanks.

How to determine if an NSDate is today?

Swift

如何检查NSDate是否属于今天？我过去常常使用[aDate description]中的前10个字符来检查它。[[aDate description] substringToIndex:10]返回类似于"YYYY-MM-DD"的字符串，所以我将该字符串与[[[NSDate date] description] sub...

问如何确定NSDate是否是今天的？
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