在 Cocoa 中获取文件的类型 [英] Get the type of a file in Cocoa

问题描述

我成功地找到了指定文件的扩展文件类型(JPEG 图像、TIFF 图像等)，但我正在寻找更通用的东西，可以将文件分类为大类别"，如图像、moovies、文本文件, ...有没有办法在可可(或 Objective-c)中实现这一点?

I succeeded to find the extended file type of a specified file ( JPEG image, TIFF Image, ...) but I am looking for something more generic that can categorize files in "big cathegories" like images, moovies, text files, ... It there a way to acheive this in cocoa (or objective-c) ?

感谢您的帮助，

推荐答案

你可以使用 统一类型标识符.由于 UTI 被组织成层次结构，一种可能性是检查给定文件的首选 UTI 是否符合顶级 UTI，例如public.image 用于图像或 public.movi​​e 用于电影.核心服务框架包括对 UTI 进行操作的函数以及表示已知 UTI 的常量.

You could use Uniform Type Identifiers. Since UTIs are organised into hierarchies, one possibility is to check whether the preferred UTI for a given file conforms to a top-level UTI, e.g. public.image for images or public.movie for movies. The Core Services framework includes functions that operate on UTIs as well as constants representing known UTIs.

例如，处理文件扩展名:

For instance, working on file name extensions:

NSString *file = @"…"; // path to some file
CFStringRef fileExtension = (CFStringRef) [file pathExtension];
CFStringRef fileUTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, fileExtension, NULL);

if (UTTypeConformsTo(fileUTI, kUTTypeImage)) NSLog(@"It's an image");
else if (UTTypeConformsTo(fileUTI, kUTTypeMovie)) NSLog(@"It's a movie");
else if (UTTypeConformsTo(fileUTI, kUTTypeText)) NSLog(@"It's text");

CFRelease(fileUTI);

如果您有 MIME 类型而不是文件扩展名，则可以使用 kUTTagClassMIMEType 而不是 kUTTagClassFilenameExtension.

If you have a MIME type instead of a file name extension, you can use kUTTagClassMIMEType instead of kUTTagClassFilenameExtension.

有关已知 UTI 的列表，请参阅 本文档.

For a list of known UTIs, see this document.

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