blocks|key|1337537|text|mach_absolute_time()可用于获得精确的测量结果。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1337538|请参阅http://developer.apple.com/qa/qa2004/qa1398.html|1337539|CACurrentMediaTime()也是可用的，它本质上是相同的，但具有更容易使用的界面。|1337540|(注:此答案写于2009年。有关较新版本的macOS和iOS中提供的更简单的POSIX+clock_gettime()接口，请参阅Pavel+Alexeev的答案。)|1337541|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/qa/qa2004/qa1398.html^0|0|K|0|3|1C|0|0|0|K|0|18|F|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|H|3|I|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|L|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S]]]]

<code>mach_absolute_time()</code> can be used to get precise measurements.
See <a href="http://developer.apple.com/qa/qa2004/qa1398.html" rel="nofollow noreferrer">http://developer.apple.com/qa/qa2004/qa1398.html</a>
Also available is <code>CACurrentMediaTime()</code>, which is essentially the same thing but with an easier-to-use interface.
(Note: This answer was written in 2009. See Pavel Alexeev's answer for the simpler POSIX <code>clock_gettime()</code> interfaces available in newer versions of macOS and iOS.)

blocks|key|1337758|text|此外，如果您想要在CoreData中存储64位NSNumber，下面是如何计算以毫秒为单位的Unix纪元初始化的64位you。我需要在我的应用程序中使用它，它与以这种方式存储日期的系统进行交互。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1337759|++%2B+(NSNumber*)+longUnixEpoch+{
++++++return+[NSNumber+numberWithLongLong:[[NSDate+date]+timeIntervalSince1970]+*+1000];
++}|code-block|syntax|javascript|1337760|entityMap^0|N|8|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|$]]

Also, here is how to calculate a 64-bit <code>NSNumber</code> initialized with the Unix epoch in milliseconds, in case that is how you want to store it in CoreData. I needed this for my app which interacts with a system that stores dates this way.

<pre><code> + (NSNumber*) longUnixEpoch {
 return [NSNumber numberWithLongLong:[[NSDate date] timeIntervalSince1970] * 1000];
 }
</code></pre>

blocks|key|1553557|text|我知道这是一个老版本，但我发现自己又一次错过了它，所以我想我应该在这里提交我自己的选项。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1553558|最好的办法是查看我的博客文章：Timing+things+in+Objective-C:+A+stopwatch|offset|length|1553559|基本上，我写了一个类，它以一种非常基本的方式停止监视，但被封装了，因此您只需执行以下操作：|1553560|[MMStopwatchARC+start:@"My+Timer"];
//+your+work+here+...
[MMStopwatchARC+stop:@"My+Timer"];|code-block|syntax|javascript|1553561|你最终会得到：|1553562|MyApp[4090:15203]++->+Stopwatch:+[My+Timer]+runtime:+[0.029]|1553563|在日志中...|1553564|同样，请查看我的帖子以获取更多信息，或在此处下载：MMStopwatch.zip|1553565|entityMap|0|LINK|mutability|MUTABLE|url|http://metal-sole.com/2012/01/24/timing-things-in-objective-c-a-stopwatch/|1|http://metal-sole.com/wp-content/uploads/2012/01/MMStopwatch.zip^0|0|F|15|0|0|0|0|0|0|0|P|F|1|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@$D|16|E|17|1|18]]|A|$]]|$1|F|3|G|5|6|7|19|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1A|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1B|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|1C|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1D|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1E|8|@]|9|@$D|1F|E|1G|1|1H]]|A|$]]|$1|U|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]|12|$5|X|Y|Z|A|$10|13]]]]

I know this is an old one but even I found myself wandering past it again, so I thought I'd submit my own option here.

Best bet is to check out my blog post on this:
<a href="http://metal-sole.com/2012/01/24/timing-things-in-objective-c-a-stopwatch/" rel="nofollow">Timing things in Objective-C: A stopwatch</a>

Basically, I wrote a class that does stop watching in a very basic way but is encapsulated so that you only need to do the following:

<pre><code>[MMStopwatchARC start:@"My Timer"];
// your work here ...
[MMStopwatchARC stop:@"My Timer"];
</code></pre>

And you end up with:

<pre><code>MyApp[4090:15203] -&gt; Stopwatch: [My Timer] runtime: [0.029]
</code></pre>

in the log...

Again, check out my post for a little more or download it here:
<a href="http://metal-sole.com/wp-content/uploads/2012/01/MMStopwatch.zip" rel="nofollow">MMStopwatch.zip</a>

blocks|key|1553598|text|#define+CTTimeStart()+NSDate+*+__date+=+[NSDate+date]
#define+CTTimeEnd(MSG)+NSLog(MSG+"+%25g",[__date+timeIntervalSinceNow]*-1)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1553599|用法：|unstyled|1553600|CTTimeStart();
...
CTTimeEnd(@"that+was+a+long+time:");|1553601|输出：|1553602|2013-08-23+15:34:39.558+App-Dev[21229:907]+that+was+a+long+time:+.0023|1553603|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|P|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|I|3|J|5|F|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|M|3|-4|5|F|7|T|8|@]|9|@]|A|$]]]|N|$]]

<pre><code>#define CTTimeStart() NSDate * __date = [NSDate date]
#define CTTimeEnd(MSG) NSLog(MSG " %g",[__date timeIntervalSinceNow]*-1)
</code></pre>

Usage:

<pre><code>CTTimeStart();
...
CTTimeEnd(@"that was a long time:");
</code></pre>

Output:

<pre><code>2013-08-23 15:34:39.558 App-Dev[21229:907] that was a long time: .0023
</code></pre>

blocks|key|1553654|text|对于这些人，我们需要@Jeff+Thompson的Swift版本的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1553655|//+Get+a+current+time+for+where+you+want+to+start+measuring+from
var+date+=+NSDate()

//+do+work...

//+Find+elapsed+time+and+convert+to+milliseconds
//+Use+(-)+modifier+to+conversion+since+receiver+is+earlier+than+now
var+timePassed_ms:+Double+=+date.timeIntervalSinceNow+*+-1000.0|code-block|syntax|javascript|1553656|我希望这对你有帮助。|1553657|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|$]]

For those we need the Swift version of the answer of @Jeff Thompson: 

<pre><code>// Get a current time for where you want to start measuring from
var date = NSDate()

// do work...

// Find elapsed time and convert to milliseconds
// Use (-) modifier to conversion since receiver is earlier than now
var timePassed_ms: Double = date.timeIntervalSinceNow * -1000.0
</code></pre>

I hope this help you.

blocks|key|1553717|text|您可以使用NSDate获取自1970年1月1日以来的当前时间：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1553718|-+(double)currentTimeInMilliseconds+{
++++NSDate+*date+=+[NSDate+date];
++++return+[date+timeIntervalSince1970]*1000;
}|code-block|syntax|javascript|1553719|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 can get current time in milliseconds since January 1st, 1970 using an NSDate:

<pre><code>- (double)currentTimeInMilliseconds {
 NSDate *date = [NSDate date];
 return [date timeIntervalSince1970]*1000;
}
</code></pre>

Is there an easy way to get a time very precisely? 

I need to calculate some delays between method calls. More specifically, I want to calculate the speed of scrolling in an UIScrollView.

How can I get a precise time, for example in milliseconds in Objective-C?

Swift

Unix

有没有一种简单的方法可以非常精确地获得时间？我需要计算方法调用之间的一些延迟。更具体地说，我想计算在UIScrollView中滚动的速度。

问我怎样才能得到一个精确的时间，比如Objective-C中的毫秒？
EN

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问我怎样才能得到一个精确的时间，比如Objective-C中的毫秒？EN

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问我怎样才能得到一个精确的时间，比如Objective-C中的毫秒？
EN