The most useful non-source code resources at the time were about GCC, BSD and Apple’s PDF guides on how the OS works, and the Human Interface Guides, paid Devel

The most useful non-source code resources at the time were about GCC, BSD and Apple’s PDF guides on how the OS works, and the Human Interface Guides, paid Developer Connection accounts got you tools mailed to you and DVDs of WWDC seminars. But it’s a profession, selling shrinkwapped desktop applications or the modern equivalent takes a lot.