iPhone dev 6

Init may return a different object than was allocated. For example in singleton case it may return the already existing object. For this reason should always use the one returned by init. Objective-C seems to support exceptions (or is it a Cocoa feature? I'm confused about the distinction). Self, super. Strange plus and minus signs near method declarations. Maybe plus signs have something to do with factories? Noted in explanation about the "respondsToSelector" introspection method, that it tells if an object responds to a certain method -- so "selector" does indeed mean a method? "autorelease" was mentioned many times, but don't know what that is. Section about class clusters: public superclass with many private subclasses, you instantiate the subclasses through factory methods in the superclass. For example Number superclass which can create Ints, Floats and so on. Skipping sections about class cluster details and "creating a singleton instance". I'll return back to them if the need arises to create my own cluster objects or singletons, just too tiring to read about them now.