blocks|key|5820574|text|%5E表示Objective-C中块定义的开始。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5820575|看看这里：http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/bxGettingStarted.html#//apple_ref/doc/uid/TP40007502-CH7-SW1|5820576|请注意，在此上下文中，%5E不是运算符，它是Objective-C的语法的一部分@Mike被否决的答案严格来说是"%5E运算符“的正确定义|5820577|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/bxGettingStarted.html#//apple_ref/doc/uid/TP40007502-CH7-SW1^0|0|1|0|5|43|0|0|B|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@]|D|@$9|V|A|W|1|X]]|E|$]]|$1|H|3|I|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

The <code>^</code> indicated the start of a block definition within Objective-C. 

Have a look in here: <a href="http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/bxGettingStarted.html#//apple_ref/doc/uid/TP40007502-CH7-SW1" rel="noreferrer">http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/bxGettingStarted.html#//apple_ref/doc/uid/TP40007502-CH7-SW1</a>

Note that in this context, the <code>^</code> is not an operator, it is part of the syntax of Objective-C @Mike's down-voted answer is strictly the correct definition of the "^ operator"

blocks|key|344253|text|它用于在对象c中创建块，块就像c中的函数指针。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|344254|checkout+this+link|offset|length|344255|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/#documentation/cocoa/conceptual/Blocks/Articles/00_Introduction.html^0|0|0|I|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

It is used to create blocks in object c blocks are just like function pointers in c. This may help you 

<a href="http://developer.apple.com/library/ios/#documentation/cocoa/conceptual/Blocks/Articles/00_Introduction.html" rel="nofollow">checkout this link</a>

blocks|key|2467283|text|这是一个开始一个块的信号。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2467284|你可以通过阅读一些教程博客或文章找到更多关于block的信息：|2467285|Blocks+–+An+Interesting+Objective-C+Addition+In+iOS+4|offset|length|2467286|How+To+Use+Blocks+in+iOS+5+Tutorial|2467287|当您了解了块的基本知识后，您可以参考Apple's+document+about+block。|2467288|事实上，最常用的块将是GCD(代表中央调度中心，这是您的问题)，UIView's+animation和其他类似回调的东西。它在现代Obj-C编程中非常有用和普遍。|2467289|entityMap|0|LINK|mutability|MUTABLE|url|http://maniacdev.com/2010/07/blocks-an-interesting-objective-c-addition-in-ios-4/|1|http://www.raywenderlich.com/9438/how-to-use-blocks-in-ios-5-tutorial-part-2|2|http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/00_Introduction.html|3|https://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html|4|http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIView_Class/UIView/UIView.html#//apple_ref/occ/cl/UIView^0|0|0|0|1H|0|0|0|Z|1|0|I|S|2|0|B|3|3|W|I|4|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|14|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|15|8|@]|9|@$F|16|G|17|1|18]]|A|$]]|$1|H|3|I|5|6|7|19|8|@]|9|@$F|1A|G|1B|1|1C]]|A|$]]|$1|J|3|K|5|6|7|1D|8|@]|9|@$F|1E|G|1F|1|1G]]|A|$]]|$1|L|3|M|5|6|7|1H|8|@]|9|@$F|1I|G|1J|1|1K]|$F|1L|G|1M|1|1N]]|A|$]]|$1|N|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]]|O|$P|$5|Q|R|S|A|$T|U]]|V|$5|Q|R|S|A|$T|W]]|X|$5|Q|R|S|A|$T|Y]]|Z|$5|Q|R|S|A|$T|10]]|11|$5|Q|R|S|A|$T|12]]]]

Here it is a signal for beginning a block. 

You can find more information of block by reading some tutorial blogs or articles:

<a href="http://maniacdev.com/2010/07/blocks-an-interesting-objective-c-addition-in-ios-4/" rel="nofollow">Blocks – An Interesting Objective-C Addition In iOS 4</a>

<a href="http://www.raywenderlich.com/9438/how-to-use-blocks-in-ios-5-tutorial-part-2" rel="nofollow">How To Use Blocks in iOS 5 Tutorial</a> 

When you know the basic thing of block, you can refer to <a href="http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/00_Introduction.html" rel="nofollow">Apple's document about block</a>.

In fact, the most regular use of block will be <a href="https://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html" rel="nofollow">GCD</a>(stands for Grand Central Dispatch, which is your case in question), <a href="http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIView_Class/UIView/UIView.html#//apple_ref/occ/cl/UIView" rel="nofollow">UIView's animation</a> and something other like a callback. It is very useful and common in modern Obj-C programming.

blocks|key|5820675|text|它在Objective+C中称为块|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|5820676|语法：|5820677|returnType+(%5EvariableName)(parameters);|code-block|syntax|javascript|5820678|从tutorial+by+Akiel+Khan逐字摘录(您可以找到另一个很好的教程here)：|5820679|5820680|blockquote|5820681|5820682|5820683|块文字是“匿名的”(即无名的)|unordered-list-item|5820684|插入符号(%5E)+|5820685|我们不必指定返回类型-编译器可以“推断”它。如果我们想的话，我们可以明确地提到这一点。|5820686|5820687|This+is+a+Official+Documentation,+read+it+for+more+information.|5820688|entityMap|0|LINK|mutability|MUTABLE|url|http://code.tutsplus.com/tutorials/understanding-objective-c-blocks--mobile-14319|1|https://web.archive.org/web/20131025011421/http://informalprotocol.com/2012/10/declaring-blocks-in-objective-c|2|http://developer.apple.com/library/ios/#documentation/cocoa/conceptual/ProgrammingWithObjectiveC/WorkingwithBlocks/WorkingwithBlocks.html^0|G|1|0|0|0|1|M|0|15|4|1|0|0|0|0|0|0|0|0|0|0|1R|2|0^^$0|@$1|2|3|4|5|6|7|1F|8|@$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1I|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1J|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1K|8|@]|D|@$9|1L|A|1M|1|1N]|$9|1O|A|1P|1|1Q]]|E|$]]|$1|O|3|-4|5|6|7|1R|8|@]|D|@]|E|$]]|$1|P|3|-4|5|Q|7|1S|8|@]|D|@]|E|$]]|$1|R|3|-4|5|6|7|1T|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1U|8|@]|D|@]|E|$]]|$1|T|3|U|5|V|7|1V|8|@]|D|@]|E|$]]|$1|W|3|X|5|V|7|1W|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|V|7|1X|8|@]|D|@]|E|$]]|$1|10|3|-4|5|6|7|1Y|8|@]|D|@]|E|$]]|$1|11|3|12|5|6|7|1Z|8|@]|D|@$9|20|A|21|1|22]]|E|$]]|$1|13|3|-4|5|6|7|23|8|@]|D|@]|E|$]]]|14|$15|$5|16|17|18|E|$19|1A]]|1B|$5|16|17|18|E|$19|1C]]|1D|$5|16|17|18|E|$19|1E]]]]

It is called a Block In Objective C

Syntax:

<pre><code>returnType (^variableName)(parameters);
</code></pre>

Taken verbatim from a <a href="http://code.tutsplus.com/tutorials/understanding-objective-c-blocks--mobile-14319" rel="nofollow">tutorial by Akiel Khan</a>, (you can find another good tutorial <a href="https://web.archive.org/web/20131025011421/http://informalprotocol.com/2012/10/declaring-blocks-in-objective-c" rel="nofollow">here</a>) :

<blockquote>
 <ul>
 <li>The block literal is “anonymous” (i.e. nameless)</li>
 <li>The caret (^) symbol</li>
 <li>We didn’t have to specify the return type – the compiler can “infer” it. We could’ve explicitly mentioned it if we wanted to.</li>
 </ul>
</blockquote>

<a href="http://developer.apple.com/library/ios/#documentation/cocoa/conceptual/ProgrammingWithObjectiveC/WorkingwithBlocks/WorkingwithBlocks.html" rel="nofollow">This is a Official Documentation, read it for more information.</a>

I'm a newbie in Objective C and trying to figure out what does the ^ operator? While exploring some source code i saw next construction:

<pre><code>dispatch_once(&amp;onceToken, ^{
 UIGraphicsBeginImageContextWithOptions(CGSizeMake(20.f, 13.f), NO, 0.0f);

 [[UIColor blackColor] setFill];
 [[UIBezierPath bezierPathWithRect:CGRectMake(0, 0, 20, 1)] fill];
 [[UIBezierPath bezierPathWithRect:CGRectMake(0, 5, 20, 1)] fill];
 [[UIBezierPath bezierPathWithRect:CGRectMake(0, 10, 20, 1)] fill];

 [[UIColor whiteColor] setFill];
 [[UIBezierPath bezierPathWithRect:CGRectMake(0, 1, 20, 2)] fill];
 [[UIBezierPath bezierPathWithRect:CGRectMake(0, 6, 20, 2)] fill];
 [[UIBezierPath bezierPathWithRect:CGRectMake(0, 11, 20, 2)] fill]; 

 defaultImage = UIGraphicsGetImageFromCurrentImageContext();
 UIGraphicsEndImageContext();

});
</code></pre>

And I'd like to know what is the ^?

Objective-C the ^ operator

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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我是Objective C的新手，正在尝试弄清楚^运算符是什么？在探索一些源代码时，我看到了下面的结构：dispatch_once(&onceToken, ^{    UIGraphicsBeginImageContextWithOptions(CGSizeMake(20.f, 13.f), NO, 0.0f);   ...

问Objective-C的^运算符
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问Objective-C的^运算符EN