Re: Attributed strings and custom attributes

FROM : Douglas Davidson
DATE : Thu Jul 20 18:53:04 2006

On Jul 20, 2006, at 5:56 AM, Jeremy Dronfield wrote:

> Has anyone come up with a way of getting custom attributes on an 
> attributed string to save?
>
> I'm using -[NSAttributedString 
> RTFDFileWrapperFromRange:documentAttributes:] to save the contents 
> of a text view containing text with custom attributes. (The value 
> of the custom attribute type is an NSDictionary containing 
> metadata. The metadata is related to an NSTextAttachment which is 
> added to the same piece of text as the custom attribute.)  When the 
> file is reloaded into the text view, my custom attributes have 
> disappeared. A trawl of the archives suggests that this has been a 
> perennial problem, but offers no solutions other than archiving, 
> which is of no use to me in this situation.
>


This is a difficult problem, and one that has been on our minds.  It 
is technically possible to include custom information within RTF, but 
it is not easy to provide a generalized facility for doing so.  For 
now, if you wish to have RTFD-persistent information associated with 
attachments, you will need to include it by some means or other with 
the contents of the attached files.

For example, you could write out a container file of some sort that 
includes both your metadata and the actual contents of the original 
attached file, and then split out the two parts after reading in the 
document.  Alternatively, it would also be possible to add additional 
files to the RTFD file wrapper, alongside the attached files, but you 
would need to arrange a mapping between the attached files and the 
metadata files.  As another alternative, you could add a single 
additional attached file at the end of the document, representing a 
dictionary of dictionaries mapping from attached files to metadata 
dictionaries.

Douglas Davidson