Learn Object-C On Mac -- chapter2笔记

--What’s a framework? We’re glad you asked. A framework is a collection of parts—headerfiles, libraries, images, sounds, and more—collected together into a single unit. Apple ships technologies such as Cocoa, Carbon, QuickTime, and OpenGL as sets of frameworks. Cocoa consists of a pair of frameworks, Foundation and Application Kit (also known as AppKit),along with a suite of supporting frameworks, including Core Animation and Core Image,which add all sorts of cool stuff to Cocoa.

NSLog() is a Cocoa function that works very much like
printf().Just like printf(), NSLog()takes a string as its first argument.