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POIn-memory mime-type detection with Cocoa (OS X)?
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  1. POIn-memory mime-type detection with Cocoa (OS X)?
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    copied!<p>My application is a viewer for a custom format, a zip file with a well defined XML manifest and resources, such as images and movies. I use zlib to open up the zip file in memory and then proceed to display said resources. </p> <p>One problem I've ran into is that I'm unable to properly display videos, apparently because QTMovie cannot determine the mime-type. Movie loaded from file ([QTMovie movieWithFile]) works perfectly. Loaded from memory ([QTMovie movieWithData]) refuses to work. </p> <p>This makes sense, because lacking the file extension, QTMovie cannot determine the mime-type information. After a bit of a search, I've resorted to using QTDataReference in the following mannner:</p> <pre><code>NSData *movieData = ...read from memory...; QTDataReference *movieDataReference = [[QTDataReference alloc] initWithReferenceToData:movieData name:fileName MIMEType:@"video/x-m4v"]; QTMovie *mov = [QTMovie movieWithDataReference:movieDataReference error:&amp;err]; </code></pre> <p>This works nicely, however hardcoding MIMEType is far from ideal. I have access to the filename and the extension, so I've attempted to find the mime-type using UTI (thanks to the nice folks on #macdev):</p> <pre><code>- (NSString*)mimeTypeForExtension:(NSString*)ext { CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension,(CFStringRef)ext,NULL); return NSMakeCollectable(UTTypeCopyPreferredTagWithClass((CFStringRef)UTI,kUTTagClassMIMEType)); } </code></pre> <p>This however doesn't work. Clearly, there's an internal OS X database of extensions and corresponding mime-types, somewhere. Otherwise from-disk movies wouldn't work. How do I get access to it?</p> <p>Thanks!</p>
 

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