blocks|key|439361|text|您在中缺少NSDayCalendarUnit|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|439362|NSDateComponents+*components+=+[cal+components:(+NSMonthCalendarUnit+%7C+NSYearCalendarUnit+%7C+NSHourCalendarUnit+%7C+NSMinuteCalendarUnit+%7C+NSSecondCalendarUnit+)+fromDate:date];|code-block|syntax|javascript|439363|entityMap^0|5|H|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You are missing <code>NSDayCalendarUnit</code> in 

<pre><code>NSDateComponents *components = [cal components:( NSMonthCalendarUnit | NSYearCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:date];
</code></pre>

blocks|key|439380|text|组件中缺少NSDayCalendarUnit。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|439381|entityMap^0|5|H|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

You are missing <code>NSDayCalendarUnit</code> in the components.

blocks|key|221165|text|每日开始/每日结束- Swift+4|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221166|++//+Extension

extension+Date+{
++++var+startOfDay:+Date+{
++++++++return+Calendar.current.startOfDay(for:+self)
++++}

++++var+endOfDay:+Date+{
++++++++var+components+=+DateComponents()
++++++++components.day+=+1
++++++++components.second+=+-1
++++++++return+Calendar.current.date(byAdding:+components,+to:+startOfDay)!
++++}

++++var+startOfMonth:+Date+{
++++++++let+components+=+Calendar.current.dateComponents([.year,+.month],+from:+startOfDay)
++++++++return+Calendar.current.date(from:+components)!
++++}

++++var+endOfMonth:+Date+{
++++++++var+components+=+DateComponents()
++++++++components.month+=+1
++++++++components.second+=+-1
++++++++return+Calendar.current.date(byAdding:+components,+to:+startOfMonth)!
++++}
}

//+End+of+day+=+Start+of+tomorrow+minus+1+second
//+End+of+month+=+Start+of+next+month+minus+1+second|code-block|syntax|javascript|221167|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|$]]

<h1>Start Of Day / End Of Day — Swift 4</h1>
<pre><code> // Extension

extension Date {
 var startOfDay: Date {
 return Calendar.current.startOfDay(for: self)
 }

 var endOfDay: Date {
 var components = DateComponents()
 components.day = 1
 components.second = -1
 return Calendar.current.date(byAdding: components, to: startOfDay)!
 }

 var startOfMonth: Date {
 let components = Calendar.current.dateComponents([.year, .month], from: startOfDay)
 return Calendar.current.date(from: components)!
 }

 var endOfMonth: Date {
 var components = DateComponents()
 components.month = 1
 components.second = -1
 return Calendar.current.date(byAdding: components, to: startOfMonth)!
 }
}

// End of day = Start of tomorrow minus 1 second
// End of month = Start of next month minus 1 second
</code></pre>

blocks|key|439424|text|您不必将组件设置为零，只需忽略它们：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|439425|-(NSDate+*)beginningOfDay:(NSDate+*)date
{
++++NSCalendar+*calendar+=+[NSCalendar+currentCalendar];
++++NSDateComponents+*components+=+[calendar+components:NSYearCalendarUnit+%7C+NSMonthCalendarUnit+%7C+NSDayCalendarUnit+fromDate:date];
++++return+[calendar+dateFromComponents:components];
}|code-block|syntax|javascript|439426|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|$]]

You don't have to set up the components to zero, just ignore them:

<pre><code>-(NSDate *)beginningOfDay:(NSDate *)date
{
 NSCalendar *calendar = [NSCalendar currentCalendar];
 NSDateComponents *components = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:date];
 return [calendar dateFromComponents:components];
}
</code></pre>

blocks|key|221210|text|另一种获取结果的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221211|NSDate+*date+=+[NSDate+date];

NSDateComponents+*components+=+[[NSDateComponents+alloc]+init];
components.day+=+[[NSCalendar+currentCalendar]+ordinalityOfUnit:(NSCalendarUnitDay)+inUnit:(NSCalendarUnitEra)+forDate:date];
NSDate+*dayBegin+=+[[NSCalendar+currentCalendar]+dateFromComponents:components];

components.day+%2B=+1;
NSDate+*dayEnd+=+[[NSCalendar+currentCalendar]+dateFromComponents:components];|code-block|syntax|javascript|221212|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|$]]

One more way to get result:

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

NSDateComponents *components = [[NSDateComponents alloc] init];
components.day = [[NSCalendar currentCalendar] ordinalityOfUnit:(NSCalendarUnitDay) inUnit:(NSCalendarUnitEra) forDate:date];
NSDate *dayBegin = [[NSCalendar currentCalendar] dateFromComponents:components];

components.day += 1;
NSDate *dayEnd = [[NSCalendar currentCalendar] dateFromComponents:components];
</code></pre>

blocks|key|221256|text|对我来说，在stackoverflow上没有一个答案是有效的。为了开始今天的学习，我这样做了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221257|NSCalendar+*+gregorian+=+[[NSCalendar+alloc]+initWithCalendarIdentifier:NSCalendarIdentifierGregorian];+
[gregorian+setTimeZone:[NSTimeZone+timeZoneForSecondsFromGMT:0]];++++
NSDateComponents+*components+=+[gregorian+components:NSCalendarUnitYear%7CNSCalendarUnitMonth%7CNSCalendarUnitDay+fromDate:[NSDate+date]];+
[components+setTimeZone:[NSTimeZone+timeZoneForSecondsFromGMT:0]];+
NSDate+*beginningOfToday+=+[gregorian+dateFromComponents:components];|code-block|syntax|javascript|221258|请注意这个[gregorian+setTimeZone:[NSTimeZone+timeZoneForSecondsFromGMT:0]];和[components+setTimeZone:[NSTimeZone+timeZoneForSecondsFromGMT:0]];。|offset|length|style|CODE|221259|当创建日历时，它使用当前时区进行初始化，当从其组件中提取日期时，由于NSDate没有时区，因此当前时区中的日期被视为协调世界时区。因此，我们需要在提取组件之前和以后从这些组件中提取日期时设置时区。|221260|entityMap^0|0|0|5|1T|1Z|1U|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]|$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|P|$]]

For me none of the answers here and else where on stackoverflow worked. To get start of today i did this.

<pre><code>NSCalendar * gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian]; 
[gregorian setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]]; 
NSDateComponents *components = [gregorian components:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay fromDate:[NSDate date]]; 
[components setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]]; 
NSDate *beginningOfToday = [gregorian dateFromComponents:components];
</code></pre>

Note this <code>[gregorian setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];</code> and <code>[components setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];</code>.

When a calendar is created it gets initialised with current timezone and when date is extracted from its components, since NSDate has no timezone, the date from current timezone is considered as UTC timezone. So we need to set the timezone before extracting components and later when extracting date from these components.

blocks|key|221304|text|只是使用Calendar的dateInterval(of:start:interval:for:)和专用DateInterval结构的另一种方式|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|221305|返回时，startDate包含一天的开始，interval包含一天中的秒数。|221306|func+dateInterval(of+date+:+Date)+->+DateInterval+{
++++var+startDate+=+Date()
++++var+interval+:+TimeInterval+=+0.0
++++Calendar.current.dateInterval(of:+.day,+start:+&startDate,+interval:+&interval,+for:+date)
++++return+DateInterval(start:+startDate,+duration:+interval-1)
}

let+interval+=+dateInterval(of:+Date())
print(interval.start,+interval.end)|code-block|syntax|javascript|221307|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.apple.com/documentation/foundation/dateinterval^0|4|8|D|10|1G|C|0|0|4|9|L|8|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|17|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

Just another way using <code>dateInterval(of:start:interval:for:)</code> of <code>Calendar</code> and the dedicated <a href="https://developer.apple.com/documentation/foundation/dateinterval" rel="nofollow noreferrer">DateInterval</a> struct
On return <code>startDate</code> contains the start of the day and <code>interval</code> the number of seconds in the day.
<pre><code>func dateInterval(of date : Date) -&gt; DateInterval {
 var startDate = Date()
 var interval : TimeInterval = 0.0
 Calendar.current.dateInterval(of: .day, start: &amp;startDate, interval: &amp;interval, for: date)
 return DateInterval(start: startDate, duration: interval-1)
}

let interval = dateInterval(of: Date())
print(interval.start, interval.end)
</code></pre>

blocks|key|439591|text|由于iOS+8.0%2B+/+macOS+10.12%2B+/+tvOS+10.0%2B+/+watchOS+3.0%2B在基础中有一个内置函数，您可以开箱即用。不需要实现自己的函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|439592|public+func+startOfDay(for+date:+Date)+->+Date|439593|所以你可以这样使用它：|439594|let+midnightDate+=+Calendar(identifier:+.gregorian).startOfDay(for:+Date())|439595|值得记住的是，这需要考虑设备时区。如果你想使用UTC+zone，你可以在calendar上设置.timeZone。|439596|链接到苹果参考页面：https://developer.apple.com/reference/foundation/nscalendar/1417161-startofday。|439597|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.apple.com/reference/foundation/nscalendar/1417161-startofday^0|2|1F|0|0|1A|0|0|0|23|0|10|8|1B|9|0|A|26|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|13|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|L|3|M|5|6|7|17|8|@$9|18|A|19|B|C]|$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|N|3|O|5|6|7|1C|8|@]|D|@$9|1D|A|1E|1|1F]]|E|$]]|$1|P|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|Q|$R|$5|S|T|U|E|$V|W]]]]

Since <code>iOS 8.0+ / macOS 10.12+ / tvOS 10.0+ / watchOS 3.0+</code> there is a built in function in the Foundation, which you can use out of the box. No need to implement own functions.

<code>public func startOfDay(for date: Date) -&gt; Date</code>

So you can use it this way:

<code>let midnightDate = Calendar(identifier: .gregorian).startOfDay(for: Date())</code>

It's worth to remember, that this takes upon consideration the device time zone. You can set <code>.timeZone</code> on <code>calendar</code> if you want to have eg UTC zone.

Link to the Apple reference pages: <a href="https://developer.apple.com/reference/foundation/nscalendar/1417161-startofday" rel="nofollow noreferrer">https://developer.apple.com/reference/foundation/nscalendar/1417161-startofday</a>.

blocks|key|221364|text|extension+Date+{
++++func+stringFrom(dateFormat:+String)+->+String+{
++++++++let+formatter+=+DateFormatter()
++++++++formatter.dateFormat+=+dateFormat
++++++++return+formatter.string(from:+self)
++++}

++++func+firstSecondInDay()+->+Date+{
++++++++let+dayStr+=+self.stringFrom(dateFormat:+"yyyy-MM-dd")
++++++++let+firstSecondStr+=+"\(dayStr)+00:00:00"
++++++++let+format+=+DateFormatter()
++++++++format.dateFormat+=+"yyyy-MM-dd+HH:mm:ss"
++++++++return+format.date(from:+firstSecondStr)!
++++}

++++func+lastSecondInDay()+->+Date+{
++++++++let+dayStr+=+self.stringFrom(dateFormat:+"yyyy-MM-dd")
++++++++let+laseSecondStr+=+"\(dayStr)+23:59:59"
++++++++let+format+=+DateFormatter()
++++++++format.dateFormat+=+"yyyy-MM-dd+HH:mm:ss"
++++++++return+format.date(from:+laseSecondStr)!
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|221365|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>extension Date {
 func stringFrom(dateFormat: String) -&gt; String {
 let formatter = DateFormatter()
 formatter.dateFormat = dateFormat
 return formatter.string(from: self)
 }

 func firstSecondInDay() -&gt; Date {
 let dayStr = self.stringFrom(dateFormat: "yyyy-MM-dd")
 let firstSecondStr = "\(dayStr) 00:00:00"
 let format = DateFormatter()
 format.dateFormat = "yyyy-MM-dd HH:mm:ss"
 return format.date(from: firstSecondStr)!
 }

 func lastSecondInDay() -&gt; Date {
 let dayStr = self.stringFrom(dateFormat: "yyyy-MM-dd")
 let laseSecondStr = "\(dayStr) 23:59:59"
 let format = DateFormatter()
 format.dateFormat = "yyyy-MM-dd HH:mm:ss"
 return format.date(from: laseSecondStr)!
 }
}
</code></pre>

blocks|key|221437|text|这是我在Swift+4.2中使用的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221438|++++let+calendar+=+Calendar.current
++++let+fromDate+=+calendar.startOfDay(for:+Date())
++++let+endDate+=+calendar.date(bySettingHour:+23,+minute:+59,+second:+59,+of:+Date())|code-block|syntax|javascript|221439|对我来说很有吸引力。您可以将其添加到Date的开始日期和结束日期的扩展中，但是请记住，添加扩展会增加编译时间(除非在与类相同的文件中)，因此如果您只在一个位置或一个类中需要它...不要使用扩展名。|offset|length|style|CODE|221440|entityMap^0|0|0|I|4|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

This is what I use for Swift 4.2:

<pre><code> let calendar = Calendar.current
 let fromDate = calendar.startOfDay(for: Date())
 let endDate = calendar.date(bySettingHour: 23, minute: 59, second: 59, of: Date())
</code></pre>

Works like a charm for me.
You could add this to an extension for start and end dates on <code>Date</code>, however keep in mind that adding an extension increases compile time (unless in the same file as the class), so if you only need it at one place or in one class... don't use an extension.

blocks|key|439731|text|日历单位应该被认为是间隔。从iOS+10开始，Calendar有一些很好的方法来解决这一问题|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|439732|let+day+=+Calendar.autoupdatingCurrent.dateInterval(of:+.day,+for:+Date())
day?.start
day?.end.addingTimeInterval(-1)|code-block|syntax|javascript|439733|您可以使用相同的方法来获取任何日历组件(周/月/年等)的开始/结束|439734|这里需要注意的是，没有一个时间点可以定义为结束(假设我们有一个开始)。以上将在一天结束前一秒钟(23:59:59)。|439735|entityMap^0|N|8|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|V|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

Calendar units should be thought of as intervals. As of iOS 10 <code>Calendar</code> has some nice methods for this
<pre><code>let day = Calendar.autoupdatingCurrent.dateInterval(of: .day, for: Date())
day?.start
day?.end.addingTimeInterval(-1)
</code></pre>
You can use the same method, to get the start/end of any calendar component (week/month/year etc)
The caveat here is that there isn't a single point in time that can be defined as the end (given that we have a start). The above will give one second before the end of the day (23:59:59).

blocks|key|439763|text|在Swift+3及以上版本中|type|unstyled|depth|inlineStyleRanges|entityRanges|data|439764|extension+Date+{
++++var+startOfDayDate:+Date+{
++++++++return+Calendar.current.startOfDay(for:+self)
++++}

++++var+endOfDayDate:+Date+{
++++++++let+nextDayDate+=+Calendar.current.date(byAdding:+.day,+value:+1,+to:+self.startOfDayDate)!
++++++++return+nextDayDate.addingTimeInterval(-1)
++++}
}|code-block|syntax|javascript|439765|用法：|439766|var+currentDayStart+=+Date().startOfDayDate
var+currentDayEnd+=+Date().endOfDayDate|439767|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

In Swift 3 and above

<pre><code>extension Date {
 var startOfDayDate: Date {
 return Calendar.current.startOfDay(for: self)
 }

 var endOfDayDate: Date {
 let nextDayDate = Calendar.current.date(byAdding: .day, value: 1, to: self.startOfDayDate)!
 return nextDayDate.addingTimeInterval(-1)
 }
}
</code></pre>

Usage:

<pre><code>var currentDayStart = Date().startOfDayDate
var currentDayEnd = Date().endOfDayDate
</code></pre>

blocks|key|221572|text|我认为在Swift中做到这一点最简洁的方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221573|extension+Date+{
++++func+startOfDay()+->+Date+{
++++++++return+Calendar.current.startOfDay(for:+self)
++++}
++++func+endOfDay()+->+Date+{
++++++++return+Calendar.current.date(bySettingHour:+23,+minute:+59,+second:+59,+of:+self)+??+self
++++}
}|code-block|syntax|javascript|221574|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|$]]

I think the most succinct way to do this in Swift is as follows:
<pre><code>extension Date {
 func startOfDay() -&gt; Date {
 return Calendar.current.startOfDay(for: self)
 }
 func endOfDay() -&gt; Date {
 return Calendar.current.date(bySettingHour: 23, minute: 59, second: 59, of: self) ?? self
 }
}
</code></pre>

blocks|key|439911|text|在Swift+5.3中，Calendar.current.startOfDay()和Calendar.current.date(bySettingHour:，minute:，second:，of:)都是特定于时区的。如果您希望您的日期标准化为相同的时间，而不考虑时区，则应使用如下所示的GMT时间。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|439912|//+Normalize+time+of+aDate+to+12:00+GMT
let+aDate+=+Date()
let+twelveGMT+=+12+%2B+TimeZone.current.secondsFromGMT()+/+3600
let+normalizedDate+=+Calendar.current.date(bySettingHour:+twelveGMT,+minute:+0,+second:+0,+of:+aDate)|code-block|syntax|javascript|439913|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|$]]

In Swift 5.3, both Calendar.current.startOfDay() and Calendar.current.date(bySettingHour:, minute:, second:, of:) are timezone specific. If you want your date to normalize to the same time regardless of timezone, you should use GMT time like this.
<pre><code>// Normalize time of aDate to 12:00 GMT
let aDate = Date()
let twelveGMT = 12 + TimeZone.current.secondsFromGMT() / 3600
let normalizedDate = Calendar.current.date(bySettingHour: twelveGMT, minute: 0, second: 0, of: aDate)
</code></pre>

blocks|key|440055|text|因为Calendar结构包含startOfDay(for:)，所以我发现最好将endOfDay(for:)方法封装在Calendar的扩展中，而不是Date中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|440056|下面的代码可以放在一个Playground文件中，以便快速执行。|440057|import+Foundation

extension+Calendar+{

++++func+endOfDay(for+date:+Date)+->+Date+{

++++++++//+Get+the+start+of+the+date+argument.
++++++++let+dayStart+=+self.startOfDay(for:+date)

++++++++//+Add+one+day+to+the+start+of+the+day+
++++++++//+in+order+to+get+the+start+of+the+following+day.++++++++++++
++++++++guard+let+nextDayStart+=+self.date(byAdding:+.day,+value:+1,+to:+dayStart)+else+{
++++++++++++preconditionFailure("Expected+start+of+next+day")
++++++++}

++++++++//+Create+date+components+that+will+subtract+a+single
++++++++//+second+from+the+start+of+the+next+day.+This+will
++++++++//+allow+you+to+get+the+last+hour,+last+minute,+and+last
++++++++//+second+of+the+previous+day,+which+is+the+day+for+the+
++++++++//+date+argument+that+was+passed+to+this+method.
++++++++var+components+=+DateComponents()
++++++++components.second+=+-1

++++++++//+Add+the+date+components+to+the+date+for+the+next+
++++++++//+day,+which+will+perform+the+subtraction+of+the+single
++++++++//+second.+This+will+return+the+end+of+the+day+for+the+date
++++++++//+that+was+passed+into+this+method.
++++++++guard+let+dayEnd+=+self.date(byAdding:+components,+to:+nextDayStart)+else+{
++++++++++++preconditionFailure("Expected+end+of+day")
++++++++}

++++++++//+Simply+return+the+date+value.
++++++++return+dayEnd
++++}

}|code-block|syntax|javascript|440058|要查看格式化的日期，请创建一个DateFormatter并打印输出。|440059|let+formatter+=+DateFormatter()
formatter.dateStyle+=+.long
formatter.timeStyle+=+.long
Calendar.current.endOfDay(for:+Date())+//+"Dec+31,+2020+at+11:59+PM"|440060|entityMap^0|2|8|E|G|13|E|1M|8|22|4|0|0|0|F|D|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|13|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|18|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|R|$]]

Since the <code>Calendar</code> struct contains <code>startOfDay(for:)</code>, I find it best to encapsulate an <code>endOfDay(for:)</code> method within an extension on <code>Calendar</code> rather than within <code>Date</code>.
The following code can be placed within a Playground file for quick execution.
<pre class="lang-swift prettyprint-override"><code>import Foundation

extension Calendar {

 func endOfDay(for date: Date) -&gt; Date {

 // Get the start of the date argument.
 let dayStart = self.startOfDay(for: date)

 // Add one day to the start of the day 
 // in order to get the start of the following day. 
 guard let nextDayStart = self.date(byAdding: .day, value: 1, to: dayStart) else {
 preconditionFailure(&quot;Expected start of next day&quot;)
 }

 // Create date components that will subtract a single
 // second from the start of the next day. This will
 // allow you to get the last hour, last minute, and last
 // second of the previous day, which is the day for the 
 // date argument that was passed to this method.
 var components = DateComponents()
 components.second = -1

 // Add the date components to the date for the next 
 // day, which will perform the subtraction of the single
 // second. This will return the end of the day for the date
 // that was passed into this method.
 guard let dayEnd = self.date(byAdding: components, to: nextDayStart) else {
 preconditionFailure(&quot;Expected end of day&quot;)
 }

 // Simply return the date value.
 return dayEnd
 }

}
</code></pre>
To see the formatted date, create a <code>DateFormatter</code> and print the output.
<pre class="lang-swift prettyprint-override"><code>let formatter = DateFormatter()
formatter.dateStyle = .long
formatter.timeStyle = .long
Calendar.current.endOfDay(for: Date()) // &quot;Dec 31, 2020 at 11:59 PM&quot;
</code></pre>

blocks|key|221810|text|更新@Zelko的答案以获取日历：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221811|extension+Date+{

++++func+startOfDay(in+calendar:+Calendar+=+.current)+->+Date+{
++++++++calendar.startOfDay(for:+self)
++++}

++++func+endOfDay(in+calendar:+Calendar+=+.current)+->+Date+{
++++++++var+components+=+DateComponents()
++++++++components.day+=+1
++++++++components.second+=+-1
++++++++return+calendar.date(byAdding:+components,+to:+startOfDay(in:+calendar))!
++++}

++++func+startOfMonth(in+calendar:+Calendar+=+.current)+->+Date+{
++++++++let+components+=+calendar.dateComponents([.year,+.month],+from:+startOfDay(in:+calendar))
++++++++return+calendar.date(from:+components)!
++++}

++++func+endOfMonth(in+calendar:+Calendar+=+.current)+->+Date+{
++++++++var+components+=+DateComponents()
++++++++components.month+=+1
++++++++components.second+=+-1
++++++++return+calendar.date(byAdding:+components,+to:+startOfMonth(in:+calendar))!
++++}
}|code-block|syntax|javascript|221812|注意：|221813|当您的应用程序支持更多区域时，使用正确的日历非常重要|221814|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Updating @Zelko's Answer to get the calendar:
<pre><code>extension Date {

 func startOfDay(in calendar: Calendar = .current) -&gt; Date {
 calendar.startOfDay(for: self)
 }

 func endOfDay(in calendar: Calendar = .current) -&gt; Date {
 var components = DateComponents()
 components.day = 1
 components.second = -1
 return calendar.date(byAdding: components, to: startOfDay(in: calendar))!
 }

 func startOfMonth(in calendar: Calendar = .current) -&gt; Date {
 let components = calendar.dateComponents([.year, .month], from: startOfDay(in: calendar))
 return calendar.date(from: components)!
 }

 func endOfMonth(in calendar: Calendar = .current) -&gt; Date {
 var components = DateComponents()
 components.month = 1
 components.second = -1
 return calendar.date(byAdding: components, to: startOfMonth(in: calendar))!
 }
}
</code></pre>
<h2>Note:</h2>
It is very important to use the correct calendar when your app supports more regions

<pre><code>-(NSDate *)beginningOfDay:(NSDate *)date
{
 NSCalendar *cal = [NSCalendar currentCalendar];
 NSDateComponents *components = [cal components:( NSMonthCalendarUnit | NSYearCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:date];
 
 [components setHour:0];
 [components setMinute:0];
 [components setSecond:0];
 
 return [cal dateFromComponents:components];
 
}

-(NSDate *)endOfDay:(NSDate *)date
{
 NSCalendar *cal = [NSCalendar currentCalendar];
 NSDateComponents *components = [cal components:( NSMonthCalendarUnit | NSYearCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:date];
 
 [components setHour:23];
 [components setMinute:59];
 [components setSecond:59];
 
 return [cal dateFromComponents:components];

}
</code></pre>
When I call : <code>[self endOfDay:[NSDate date]];</code>
I get the first of the month ... Why is that? I use this two methods because I need an interval that is from the first second of the first date (beginningOfDay:date1) to the last second of the second date (endOfDay:Date2) ...

NSDate beginning of day and end of day

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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-(NSDate *)beginningOfDay:(NSDate *)date{    NSCalendar *cal = [NSCalendar currentCalendar];    NSDateComponents *components = [cal components:( NSMonthCalendar...

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