On 31 May 2010, at 01:42, John Joyce wrote: > > On May 30, 2010, at 5:15 PM, julius wrote: > >> John hi >> On 30 May 2010, at 19:47, John Joyce wrote: >> >>> That's not how these constants work. >>> These are intended to be constants that return the correct type for the >>> current build of the system. >>> This protects your software from a change in the actual UTI of a common >>> type. >>> >> >> I can understand the use of constants to such a purpose. >> Hence for instance my ability to write a file as NSRTFTextDocumentType when >> in the Save panel I have opted to save it as com.apple.rtfd or as a document >> having no UTI at all. >> >> If I read a document for which I have declared no UTI then the ofType >> parameter in the readFromData:ofType:error: displays the Name I have used to >> describe that document type. On the other hand if I have used a UTI then it >> is the UTI that is passed as the ofType parameter. >> >> So if I have this correctly, in the case of files that will only ever be >> read by my application it really does not matter what extension or UTI I >> give them since it is the responsibility of my code to make sense of them. >> However, if I want to write files that other applications can read I have >> not only to provide the correct format but also the correct extension or UTI >> . Is it therefore the case that when writing files to be read by other >> applications I need not only write using the correct >> NSDocumentTypeDocumentAttribute but also provide the correct UTI (or >> extension)? If so then surely I need to have an idea of which UTI's (if any) >> go with a given NSDocumentTypeDocumentAttribute? >> >> Thanks >> Julius >> >> >> http://juliuspaintings.co.uk >> > Your application declares the types of files it can read and/or edit. > It declares these types by UTI.
That is what I thought. > > If an application declares that it can read files of type x, then you can > definitely open files of type x with that application. > > Not all UTIs are built in the OS. > They're "registered" with the OS. > The OS does not know about many (most?) file types out of the box. That too is my understanding > > The OS can attempt to identify a file's type. > It doesn't always know 100% what app should or could open a file or edit it. > It will then give you a choice of "Recommended applications", that is, apps > that are declared to read or edit a file of the UTI that the OS thinks this > file might be. The OS does allow the user to choose from "All Applications" > also, because the OS cannot realistically know about all file types ahead of > time. Which is why (I think I correctly assume) one's program has to make decisions regarding how to handle incoming or outgoing file data on the basis of the ofType: parameter. > > This data is covered, but you may want to explore further the docs, a few > books on cocoa, and sample apps from apple. > Look at how they handle this. > Ideally, look at open source or sample apps that handle similar file types to > yours. Yes. But I have!!! And am still none the wiser as to which type goes with which NSDocumentTypeDocumentAttribute. For instance I have been been studying TextEdit for a while now and seeing how it maps the files it reads and writes to the UTI's and other indications of type but it does not tell me where I can find the indicators for the mappings it does not use or the range of what is actually encompassed by the mappings that it does use. I merely wondered where to get information on the mapping between NSDocumentTypeDocumentAttribute(s) and the UTI's or other indicators of type. I guess the reason I'm having difficulties is that there ain't no such documentation? There's only 9 of these mappings of which I think I know a couple of the corresponding types but the rest are a mystery. Could you or someone else to just fill in the remaining 7 blanks for me? Also, since when I look at how spotlight types various files I can see that a file may be described by more than one UTI, Similarly the UTI reference talks of base types which implies the existence of a hierarchy (or is it a looser organisation?). Where is this actual, not theoretical, hierarchy documented? NSPlainTextDocumentType - ? NSRTFTextDocumentType - public.rtf - is this right? It looks right but I have no means other than experiential of finding out NSRTFDTextDocumentType - com.apple.rtfd - ditto here. NSMacSimpleTextDocumentType - ? NSHTMLTextDocumentType - ? NSDocFormatTextDocumentType - ? NSWordMLTextDocumentType - ? NSOfficeOpenXMLTextDocumentType - ? NSOpenDocumentTextDocumentType; - ? ------------------------------------------------------ http://juliuspaintings.co.uk _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
