used to be easier
when there was one major forum all of us watched (Usenet new group comp.sys.mac.programming). You can still find the excellent but dated FAQ for that group online, if you have the ancient tools and want to develop for OS 9 or earlier on legacy machines.
Appologies to anyone reading this in its first form, this is edited and improved.
Used to be we had a few printed and CDRom information resources and could suggest politely to RTFM (read the fine manual). Now its all on disk and the massivess of it makes finding a place to start a challenge.
There are many issues for you to conquer. Also for me, tho different ones. You will find that there is a commonality to all proceedural programming languages, much of it based on the grammer we use in mathematical equations. Some of us find it useful to explore language design as well as specific language grammar, but that goes beyond your query.
First for you is the basic concepts of programming in a procedural language (yes, there are non-procedural 'languages', Filemaker Pro is one example).
If you live near a college which has a computer science curriculum you could visit the relevant department and seek out a conveniant course to take or audit. The bookstore will have tomes of interest, consider used copies if expense is an issue. Once you master the grammer of one language it is not all that hard to learn another, especially if they are related. C came first (well, actually there was a B, but not I think an A). C was developed at Bell Labs and was licensed for free in academic use, but not for commercial use, so it was widely used at colleges thruout the US and overseas well into the 80's. C has evolved, the slightly safer form is sometimes called K&R C, and is what is mostly used today.
Object-oriented programming became a hot topic ca 1980, and while one could do that in C, the syntax was exposed and ugly, and the need for stronger typechecking was well known as well, so C++ and Objective C were independantly invented, each using different syntax. With Steve Jobs and the NeXT computer Objective C found an anchor and grew, and has come to us with cocoa.
C++ has been refined since then into an equally serious tool which had well developed programming and framework tools for developing Mac applications in legacy and carbon environments, but for reasons not to be speculated on by me has been thrown over by the new apple OS team in favor of objective C (it is the language they use for OS X and later versions).
Cocoa has no support for C++, you will need to access the cocoa interfaced routines, so you will learn Objective C. One can have mixed code, ie, some of your work can be coded in other languages such as Fortran, Forth, C, even C++; but it will be simplest if you focus on objective C.
C is primarily used in a unix OS environment, most of the books you find will cater to that. Better would be a book which focuses on Obj C in a Macintosh development environment, but dont be too fussy if you cant find one. The Mac GUI was originally developed as an alternative to the unix command-line experience, altho some of the programming tools invented for Mac use had interfaces that used both (including tools you will be using now). I dont know of any particular books to refer you to, partly for lack of a decent bookstore to browse (I live in a rural part of eastern long island).
There is a vast amount of information online, including committees you could join where future language extensions are being debated and developed.
Once you have the grammer of objective C down, you will find there is more than just the keywords of the language to be learned. Lots of code has been written, debugged, and placed in librarys for your use. You can reinvent those wheels, and sometimes you should, but often it helps to use the 'standard lib' routines. In addition, and this is where cocoa comes in, there are more extensive libraries called frameworks which you need to learn how to exploit.
Even the simplest application will find it requires an impressive amount of code just to get launched, set up its own menus, and put an initial window up on the screen. Further code is needed to support mouse clicks on the window and the menus. The beginning of that code is already written for you in a framework, you may have to add code to handle what is to be done when a mouse click invokes your menu items, but even then some of that is pretty much done already by a good framework.
Frameworks come in layers, the OS hides some of those layers behind the monlithic interface called cocoa. Above cocoa is your own code, between it and cocoa can be another layer, in the past this might have been PowerPlant, TCL, or MacApp.
Documentation is difficult to write, especially on new and unfamiliar topics with lots of detail and a short deadline - making for a high risk of errata. Technical notes result, they provide factual corrections, work-arounds, and code examples showing how to accomplish goals using the complex tools. Since 1984 the manuals documenting the Macintosh OS and its toolbox have expanded from one huge phone-book volume to the three book set (OS 5) and its 3 book extensions (OS 6) to the many volume IM set (OS 7). CUrrent documentation is published electronically on the OS X media, many many mega (giga?) bytes of it. Perhaps there are third party publications as well, there were back in the days of OS 6 when there were only some 300 tech notes to worry about.
Welcome, and good luck.
