Well, I've been there, done that... so many times. I've learnt BASIC and the machine code of a handful of different processors, from the famous oldtimers IBM 360/370 through Zilog Z80 to the Motorola 68k family or the PPC beasts. I've used such beasts as Algol, Cobol, Simula 67, or Lisp. I've tried Smalltalk and Prolog and love them still, though they are hardly practically useable. I've wrote my share of Pascal, Modula, and C++ lines. Heck, I've even truly used a front-panel of some pretty ancient HP machine. Being a WebObjects programmer, naturally I use Java every day (oh, Java! The blazing speed of Smalltalk, along with the simple elegance of C++!).
To sum it all up: if I am stuck now–more or less–with Objective C and Cocoa, it means only one thing: it is the most powerful and convenient thing I've seen so far. That's all.
Objective C
The Objective C programming language is a bastard. It is just a cross betwixt plain C and Smalltalk: a suprisingly successful and lucky cross, for it inherited all the great features of both, lacking (almost) all of their respective drawbacks. Thanks to Smalltalk, Objective C offers a clean, well-designed and powerful object abstraction–much better than, for example, Java (not speaking of uglies like C++ which only pretend they support OOP). Thanks to the C heritage, the language is simple, extremely easy to use, and yet–if need be–powerful enough.
Presumed you can read in Czech, just check my Text page: there are a few articles which describe Objective C quite well. Otherwise, a pretty good description should be available on-line from Apple (in the PDF format).
Cocoa
A good programming language is just a first step: to be truly useable, a well-designed set of libraries is needed. Luckily, for Objective C there is such a set: the Cocoa libraries were first designed in NeXT ages ago, then cleaned up in the form of an open standard OpenStep, finally improved by Apple into the current Cocoa shape.
The libraries are extremely strong and flexible, yet easy to use and convenient. Apart of the Mac OS X and OS X implementations which is owned and maintained by Apple, there is a free implementation available for almost any operating environment, known as GNUStep.
A number of articles describing Cocoa in great details including a number of examples can be found (again in the Czech language) at the MujMac site. Otherwise, you can check the Apple on-line Cocoa documentation.
