Question

In regards to iPhone development, how do you now when your using a Cocoa vs pure Objective-C objects. For example, the following are Objective-C:

• NSTimer
• NSString
• int, float
• NSMutableArray

But these are Cocoa:

• UILabel
• UIColor(?)
• UIView

And to be clear, does

Cocoa Touch == iPhone development

Cocoa == Mac OS X development

Answer 1

You’ve got it a little wrong.

NSTimer, NSString, NSMutableArray are all Cocoa. int and float are actually C, but since Objective-C is a strict superset of C, you are able to use them in your Objective-C code.

Pure Objective-C requires linking only to the Objective-C runtime library and no other frameworks or libraries. Cocoa is a framework that includes things like NSObject and NSString. Other frameworks, like AppKit, extend the Cocoa framework.

Coding in pure Objective-C usually means deriving from the root object called Object and not NSObject. Things like @implementation, @interface, @selector etc. are the Objective-C extensions to C and these are what are common in all Objective-C source, pure or not. If you want to code in pure Objective-C you cannot use anything other than your own objects derived from Object.

#import <objc/Object.h>