iPhone dev 3

NSObject is the root class for Cocoa classes. Stuff starting with UI prefix is UIKit related. Objective-C has garbage collection after version 2.0, but it cannot be used on the iPhone because of performance. Cocoa classes seem cleanly designed. Didn't encounter a regexp class, although didn't check if it's in NSString methods. Event mechanism in iPhone UIKit differs from Mac Application Kit. Looked at Objective-C example code, saw lots of weird square brackets. "id" datatype can hold any Cocoa object, so convenient for enumeration. Dynamic typing, binding, loading. New feature: "categories". By dropping mysterious @ marks in strategic places in your code, you can add methods to existing classes without subclassing. Protocols are like Java interfaces.