In order to use the ObjC.pm module, follow these steps:

 1. Find the Natural Docs directory.  On my system, it's
    /usr/share/perl5/naturaldocs.  I will call this directory
    ${NATURAL_DOCS} from now on.

 2. Copy ObjC.pm to ${NATURAL_DOCS}/Modules/NaturalDocs/Languages/.

 3. Open ${NATURAL_DOCS}/Modules/NaturalDocs/Languages.pm and look for a
    bunch of lines starting with “use NaturalDocs::Languages::”.  On my
    system, these lines are very much at the beginning of the file.

 4. When you've found the spot, insert the following line somewhere
    around there:

      use NaturalDocs::Languages::ObjC;

 5. You may want to add the following lines to your Languages.txt:

      Language: Objective-C

         Extension: h m mm
         Shebang String: objc
         Ignore Prefix in Index: MLK + -
         Line Comment: //
         Block Comment: /* */
         Package Separator: ::
         Class Prototype Enders: + - @end
         Function Prototype Enders: ; {
         Variable Prototype Enders: ; =
         Perl Package: NaturalDocs::Languages::ObjC

That's it.  Have fun!

Matthias