blocks|key|3299332|text|大约一周前我需要这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3299333|NSString+*+UTI+=+(NSString+*)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension,+
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++(CFStringRef)[myFilePath+pathExtension],+
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++NULL);|code-block|syntax|javascript|3299334|如果我在扩展名@"php“、@"jpg”、@"html“和@"ttf”上运行此命令，它将输出：|3299335|public.php-script
public.jpeg
public.html
public.truetype-ttf-font|3299336|3299337|多年后的更新11%2B+|offset|length|style|BOLD|3299338|在Swift中，有两种方法可以完成此操作，具体取决于您的部署目标：|3299339|3299340|如果要在macOS+Catalina和更早版本(在Big+Sur之前)或iOS+13和更早版本上运行：|ordered-list-item|3299341|3299342|让fileExtension+=+"html“让unmanagedString+=+UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension作为CFString，fileExtension作为CFString，nil)让typeIdentifier+=+unmanagedString?.takeRetainedValue()作为字符串？|3299343|UTTypeCreatePreferredIdentifierForTag()函数(仍然是CoreServices模块的一部分)返回一个Unmanaged<CFString>?；这是一种对CFString进行装箱的类型，您需要指示(通过.take...方法之一)内存管理语义应该是什么。|CODE|3299344|由于该函数遵循the+Create+Rule命名模式，因此它将向我们返回一个我们需要取得所有权的CFString。因此，我们使用.takeRetainedValue()将CFString的所有权从手动内存管理领域转移到ARC领域。|3299345|然后在String和CFString之间需要进行大量的桥接。|3299346|3299347|macOS+Big+Sur+(和iOS+14)获得了一个新的UniformTypeIdentifiers模块，使这一切变得非常简单：|3299348|3299349|让fileExtension)+=“fileExtension”让typeIdentifier+=+UTType(filenameExtension:+html|3299350|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029^0|0|0|0|0|0|4|6|0|0|0|0|0|0|0|13|19|C|1W|K|2M|8|3A|8|0|1C|8|1S|K|2D|8|7|F|0|0|3|6|A|8|0|0|U|M|0|0|0^^$0|@$1|2|3|4|5|6|7|1L|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1N|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|1O|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1Q|8|@$N|1R|O|1S|P|Q]]|9|@]|A|$]]|$1|R|3|S|5|6|7|1T|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1U|8|@]|9|@]|A|$]]|$1|U|3|V|5|W|7|1V|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|1W|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1X|8|@]|9|@]|A|$]]|$1|10|3|11|5|6|7|1Y|8|@$N|1Z|O|20|P|12]|$N|21|O|22|P|12]|$N|23|O|24|P|12]|$N|25|O|26|P|12]|$N|27|O|28|P|12]]|9|@]|A|$]]|$1|13|3|14|5|6|7|29|8|@$N|2A|O|2B|P|12]|$N|2C|O|2D|P|12]|$N|2E|O|2F|P|12]]|9|@$N|2G|O|2H|1|2I]]|A|$]]|$1|15|3|16|5|6|7|2J|8|@$N|2K|O|2L|P|12]|$N|2M|O|2N|P|12]]|9|@]|A|$]]|$1|17|3|-4|5|6|7|2O|8|@]|9|@]|A|$]]|$1|18|3|19|5|W|7|2P|8|@$N|2Q|O|2R|P|12]]|9|@]|A|$]]|$1|1A|3|-4|5|6|7|2S|8|@]|9|@]|A|$]]|$1|1B|3|1C|5|6|7|2T|8|@]|9|@]|A|$]]|$1|1D|3|-4|5|6|7|2U|8|@]|9|@]|A|$]]]|1E|$1F|$5|1G|1H|1I|A|$1J|1K]]]]

I needed this about a week ago:
<pre><code>NSString * UTI = (NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, 
 (CFStringRef)[myFilePath pathExtension], 
 NULL);
</code></pre>
If I run this on the extensions @&quot;php&quot;, @&quot;jpg&quot;, @&quot;html&quot;, and @&quot;ttf&quot;, it prints:
<pre><code>public.php-script
public.jpeg
public.html
public.truetype-ttf-font
</code></pre>
<hr />
Update 11+ years later:
In Swift, there are two ways to do this, depending on your deployment target:
<ol>
<li>If you want to run on macOS Catalina and earlier (before Big Sur) or iOS 13 and earlier:
<pre><code>let fileExtension = &quot;html&quot;
let unmanagedString = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension as CFString,
 fileExtension as CFString, 
 nil)

let typeIdentifier = unmanagedString?.takeRetainedValue() as String?
</code></pre>
The <code>UTTypeCreatePreferredIdentifierForTag()</code> func (still part of the <code>CoreServices</code> module) returns an <code>Unmanaged&lt;CFString&gt;?</code>; this is a type that boxes a <code>CFString</code> and you need to indicate (via one of the <code>.take...</code> methods) what the memory management semantics should be.
Since the function follows <a href="https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029" rel="nofollow noreferrer">the Create Rule</a> naming pattern, it's going to return a <code>CFString</code> to us that we need to take ownership of. Therefore we use <code>.takeRetainedValue()</code> to transfer the ownership of the <code>CFString</code> from the manual memory management world into the ARC world.
Then there's a decent amount of bridging to go from <code>String</code> to <code>CFString</code> and vice versa.
</li>
<li>macOS Big Sur (and iOS 14) got a new <code>UniformTypeIdentifiers</code> module that makes this a whole lot simpler:
<pre><code>let fileExtension = &quot;html&quot;
let typeIdentifier = UTType(filenameExtension: fileExtension)
</code></pre>
</li>
</ol>

blocks|key|3086197|text|您可以使用终端并调用mdls，它为您提供了有关特定文件类型的各种信息，包括UTI。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3086198|mdls+/myPath/to/myFile.ext|code-block|syntax|javascript|3086199|然后，mdls将在kMDItemContentTypeTree中显示相关的UTI(也可以从Cocoa+App+btw中调用mdls+)。|3086200|entityMap^0|A|4|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

You can use the Terminal and invoke mdls which gives you all kinds of information on a certain file type including UTIs.

<pre><code>mdls /myPath/to/myFile.ext
</code></pre>

mdls will then show you the associated UTIs in kMDItemContentTypeTree
(it's also possible to call mdls from within your Cocoa App btw).

I'm trying to find some way in Cocoa to translate from file extensions to Uniform Type Identifiers. That is, I want to find some way of doing this:

<pre><code>".jpg" =&gt; "public.jpeg"
".html" =&gt; "public.html" 
".ttf"=&gt; "public.truetype-font"
</code></pre>

I've searched on the NSWorkspace docs but couldn't find anything. The closest I could get was:

<pre><code>- (NSImage *)iconForFileType:(NSString *)fileType
</code></pre>

that returns the icon for a file extension, and

<pre><code>– (NSString *)preferredFilenameExtensionForType:(NSString *)typeName
</code></pre>

that does exactly the opposite of what I'm trying to do. Do any of you know how to do this?

I really hope I don't have to check for a lot of extensions by hand.

Thanks in advance.

Getting an Uniform Type Identifier for a given extension

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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我正在尝试在Cocoa中找到一些方法来将文件扩展名转换为统一类型标识符。也就是说，我想要找到一些方法来做到这一点：".jpg" => "public.jpeg"".html" => "public.html" ".ttf"=> "public.truetype-font"我搜索了NSWorkspace文档，但什么也找不...

问获取给定扩展的统一类型标识符
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