Matt Gemmell

TOLL is available now!

An action-thriller novel — book 2 in the KESTREL series.

★★★★★ — Amazon

Embedded RTFD

source 1 min read

One of our projects currently in development is, at its heart, a rich text editor. I was 
considering the issue of import/export of standard text file-formats (primarily RTF/D), 
and it occurred to me that a far better solution was available.
Since RTFD is natively supported by Cocoa, it makes sense to leverage that support 
as much as possible. Accordingly, our primary document file-format will be a package which 
simply contains an RTFD file, holding the text and conventional attachments. Also in the package 
will be a property list containing other persistent data, with an integer element for versioning.


There are several advantages to this approach:
  • Archiving/unarchiving are considerably simplified, and made more modular.
  • Versioning of file-formats is much easier to deal with, and backward- as well as forward-compatibility is readily implemented. You're just asking an NSDictionary if it has an object for a given key, after all.
  • Within a seemingly-proprietary file, you find only standard, documented formats - not the undocumented, cryptic binary format natively produced by NSArchiver etc.
  • Thus, other applications can readily make use of the files, taking either just the raw RTF/D content or choosing which of the additional attributes to respect.
  • Similarly, other apps can write/export to your format easily, if required.
  • Users can always access the data in your app's files, even if they don't have your app handy. Every OS X installation includes TextEdit.
  • Import/export of RTF/D become trivial to implement.
  • Files are much more easily verified, and corruption diagnosed.

I can only assume that many apps actually already take this approach inside their file packages.