I thought it might be useful to those who have recently approached the development of applications for Apple iPhone, compare Adobe ActionScript - the language used in Adobe Flash and Adobe Flex, more common among the neo-programmers - and Objective-C language used by Apple to develop its applications. Objective-C is in effect an object-oriented language in the pure sense, not that Actionscript is not, but Objective-C is definitely a plus because it is an extension of ANSI C and its syntax is a mix between C / C + + and Smalltalk, is a true OO (Object-oriented language). Many features of Objective-C are not present in Actionscript that, in the latest release 3.0, has been shown to grow although it is still far from the profile of a good language for object development.
Classes
For example we see how they are differently structured class definitions in ActionScript and Objective-C.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | / / Pakage - for namespacing of Adobe {pakage / / Class definition real MyClass { public class MyClass { / / Definition of ownership (public or private) myPropertyVar : String ; myPropertyVar public var: String ; / / Constructor MyClass ( ) { public function MyClass () { / / Todo } / / Public method myMethod ( ) : void { public function myMethod (): void { / / Todo } } } |
In Objective-C, the first difference (inherited from C) is the separation between the "definitions" and the implementation. In Objective-C you are always dealing with two distinct types of files:. H. M (in C we would have. H. C). Files. H (header files) contain only definitions, so no setup or implementation.
1 2 3 4 5 6 7 8 |
In the file. M we have instead:
1 2 3 4 5 6 7 | / / MyClass.m @ Implementation myClass void ) myMethod { - (Void) {myMethod / / Todo } @ End |
Objective-C manages the properties and methods in a way quite different from Actionscript. For example the method myMethod seen above is called (or invoked) in this way:
1 | ; [Self myMethod]; |
It speaks, in fact, Sending Message, rather than calling a method!
Note: this feature is real. When you invoke a method in Objective-C is called a physical address or function pointer. In Objective-C object actually sends a real message where they are asked to perform a particular "method"
The syntax with square brackets, perhaps the most difficult to digest even for ANSI C developers, will be clearer and simpler if we consider that:
1 2 3 4 5 6 7 | myClass.myMethod (); / / Is equal to ; [MyClass myMethod]; / / Or ; myClass.myPropertyVar = 1978; / / Same as 1978 ] ; [MyClass setMyPropertyVar: 1978]; |
With regard to the creation of objects, then the creation of an instance of a class, we have:
1 | MyClass = new MyClass ( ) ; var istanceMyClass: MyClass = new MyClass (); |
1 2 3 4 5 6 | [ [ MyClass alloc ] init ] ; MyClass * istanceMyClass = [[MyClass alloc] init]; / / Or simply [ MyClass alloc ] ; MyClass * istanceMyClass = [MyClass alloc]; / / Objective-C does support a single manufacturer as / / Happens in Actionscript: see for example initWithName, / / InitWithFrame or simply init |
This is just a simple help, leaving unexplored many other features Objective-C, there are concepts such as pointers (similar to the references in Actionscript - but not identical), protocols, categories and much more. If you are really disheartened in dealing with Objective-C, as I suggested before, by ANSI C games , never mind - for now - Actionscript, Javascript or PHP! The latter, knowing the ANSI C, rediscover them in a light very different.
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