Personally I would;
- First try to open it normally, that way if/when Apple add support your app will automatically get the improvement.
- If that fails, extract the UTI of the file and use UTTypeConformsTo “public.camera-raw-image” to see if it’s a RAW image. If not, abandon here.
- Most RAW formats are based upon the TIFF specification and contain a thumbnail of sorts, some contain JPEG some contain TIFF, all should be readable with CGImageSource, just loop through until you find a smaller preview. Display a dialog to the user with the preview and a message saying something like “RAW format not supported by Apple, using 3rd Party RAW converter. This may take a few moments…”. This way you make it clear to the user why it’s taking longer to open the image in your application than it does with say Adobe software.
- Let DCRaw do it’s job.
- File a feature request at Apple for the RAW format, make sure to include in the feature request that you want this for the version of the macOS that you’re using and tell them why you haven’t upgraded.
You’ll probably never get the RAW image support in the version of the macOS you’re using, and they may never add RAW support (Afterall Apple consider the iPhone to be a professional camera, bleugh). At the least you’re doing the best you can and providing them with information as to why photogs are leaving the platform, it’s up to them what they do with it.
I used to get requests to add RAW image support to my photography based applications in the past, I’d always respond and say I used Apple’s RAW converter and I’d let Apple know about the users Camera. However in recent years I don’t seem to get so many requests, I get more requests for Windows versions of my apps instead.
p.s. Send Dave Coffin an e-mail, he’s a good guy and maybe there’s something he can do to speed it up for you.