Objective-C Programming: The Big Nerd Ranch Guide

For the more curious: what about main()?

When you began learning C and Objective-C, you learned that the entry point into your program’s code is the main() function. It is absolutely true in Cocoa and Cocoa Touch development as well, although it is extremely rare to edit this function in Cocoa and Cocoa Touch applications. Open main.m, and you will see why:

return UIApplicationMain(argc, argv, nil, NSStringFromClass([BNRAppDelegate class]));

Well, that was anti-climactic. Only one line of actual code.

The UIApplicationMain function creates the necessary objects for your application to run. First, it creates a single instance of the UIApplication class. Then, it creates an instance of whatever class is denoted by the fourth and final ...