Cocoa reads and write RTF - but ignores the writing direction.
For example, you can set writing direction in a NSMutableParagraphStyle:
[paraStyle setBaseWritingDirection:NSWritingDirectionRightToLeft];
Then you can add this paragraph style to a NSTextStorage. But it will not save this attribute when you write RTF from it.
Anybody knows of open source/gnu good RTF code?
You might check GnuStep. – RobRix