The software has been ported to many flavors of UNIX and non-UNIX operating systems, with, as the name suggests, a special emphasis on portability. Ports exist for Solaris SPARC, IBM AIX PowerPC, DEC Alpha, HP-UX PA-RISC and HP-UX IA-64, Silicon Graphics IRIX MIPS, Linux, BSD and many other ports.
The compiler is compatible with, and can be used with many different C compilers, such as clang, gcc, Intel icc, Sun DeveloperStudio cc, lcc, tcc and great variety of other C compilers in order to generate optimal code for each specific platform and purpose.Because the compiler is written in itself, you'd normally start with a binary package of the software. For a few platforms, there are also packages of the shared libraries of the software, useful for applications that depend on those shared libraries :
On Linux or UNIX systems, you should install the sources of the software as follows :
Optionally for expert users porting to new or other platforms, where there is no binary package available, build objc-bootstrap-3.3.13.tar.gz.
The package contains the documentation in HTML format. The manual is also available here, and there's a note on Objective-C blocks. The text Objective-C for Unix is also a source of information on the architecture of the compiler.
Metalab : http://metalab.unc.edu/pub/Linux/devel/lang/objc/.
More Objective-C packages can be found at Metalab : http://metalab.unc.edu/pub/Linux/devel/lang/objc/.
CheezMUD, a MUD written in Objective-C, is not in the /devel/lang/objc directory, but rather in http://metalab.unc.edu/pub/Linux/games/muds/.
Richtext is an X11 / Motif / Lesstif text editor (and RTF file previewer) written in Objective-C and available at http://metalab.unc.edu/pub/Linux/apps/editors/X/.
Here's a screenshot of the Richtext previewer/editor on Slackware (or FreeBSD) with a KDE desktop and another screenshot on Solaris 11.3 (with a GNOME 2 desktop). Another screenshot on Solaris 11.4 with the GNOME 3 desktop.