Re: What REALLY determines which application opens a file?
Re: What REALLY determines which application opens a file?
- Subject: Re: What REALLY determines which application opens a file?
- From: Quincey Morris <email@hidden>
- Date: Tue, 7 Sep 2010 21:05:49 -0700
On Sep 7, 2010, at 19:21, G S wrote:
> Wow, I didn't realize this was such a mystery.
Perhaps not such a big mystery, but it's a treacherous conceptual area that perhaps sensible people don't want to venture into.
It's not clear from your original post whether you know that files don't *have* UTIs as metadata. They have extensions or file types as metadata, and the translation from file metadata to UTI is handled by Launch Services after aggregating all of the UTI definitions from installed apps, plus the UTI definitions variously built in to the frameworks. Then, for regular applications, if the document type definition contains a UTI, that definition (again, aggregated by Launch Services with other document type definitions) determines which applications are treated as candidates for opening documents based on UTI.
On top of that, Launch Services may special case file types known to QuickTime, in ways that may or may not be publicly documented, and on top of *that* the Finder may have special cases for associating files with applications outside of Launch Services.
All of this covers a lot of conceptual ground, some of which is undocumented, or at least combines new with old technologies that are documented in completely separate places.
Quirky QuickTime behaviors tend to be documented in tech notes, so you might want to spend some time researching those. Or, you can post the relevant sections of your plist file(s) -- both UTI and document type definitions -- and see if someone on the list can spot a problem. Or, you can post your question on the quicktime list, since it's probably not a Cocoa question in the end. Or, you can file a bug report citing the APIs that seem to claim to do what you want, and parse the DTS response for clues.
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