获取Cocoa中的文件类型 [英] Get the type of a file in Cocoa
问题描述
我成功找到一个指定文件（JPEG图像，TIFF图像，...）的扩展文件类型，但我正在寻找一些更通用的，可以分类文件在大导管如图像，moovies，文本文件，...
有一种方法可以在可可（或目标c）中加以实现？
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
您可以使用不同类型标识符。由于UTI被组织成层级，一种可能性是检查给定文件的优选UTI是否符合顶级UTI，例如。 public.image 用于图片或 public.movie 用于电影。核心服务框架包括对UTI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，您可以使用 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， a href =http://developer.apple.com/library/mac/#documentation/Miscellaneous/Reference/UTIRef/Articles/System-DeclaredUniformTypeIdentifiers.html>此文档。
For a list of known UTIs, see this document.
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