将mimetype转换为文件扩展名

Question

如何在xcode中将mimetype转换为文件扩展名，例如我有这个代码

File Extension     MIME Type

aifc                audio/x-aiff
avi                 video/x-msvideo
gz                  application/x-gzip
jpg                 image/jpeg

Xcode中

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
        NSString *mime      = [response MIMEType];
        NSString *extension = @"" // how to covert it ?!
}

Answer 1

包括<MobileCoreServices/MobileCoreServices.h>或<CoreServices/CoreServices.h>然后只是代码：

CFStringRef mimeType = (CFStringRef)@"audio/x-aiff";
CFStringRef uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType, NULL);
CFStringRef extension = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassFilenameExtension);

Answer 2

斯威夫特4：

导入CoreServices

response.mimeType // is Optional<String> - some : "audio/mpeg"

如何获得mp3是：

guard let mime = response.mimeType,
      let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mime as CFString, nil),
      let ext = UTTypeCopyPreferredTagWithClass(uti.takeRetainedValue(), kUTTagClassFilenameExtension) else{
   return
}

ext.takeRetainedValue() // is "mp3"

PD：考虑到Xcode不会获得未知文件的扩展，如.Storyboard或.cert，在这种情况下将退出Guard返回。