From Java To Objective-C

From Java To Objective C 

My Notes (part 1)

This is a very short introduction from my notes.

A good and complete starting point can be found by google.

I'm a java developer and when I'm going to learn objective-c for the iphone development the matching between the 2 languages became automatic.

Objective C is standard ansi C with object oriented extension.

So many OO arguments found in java can be find in objective C.

In objective C the class usually is split in two file:

• .h file for the class definition.
• .m file for the class implementation.

Let's go to see some code, this is only my simple notes.

.h file example

#import <UI/Class.h> //like import in java

//interface is a compiler directive, it tell that there is a class definiton

//myClassName the className

//NSObject the parent object

//<aProtocol> it respect the protocol definition (like abstract class in java)

@interface MyClassName: NSObject <aProtocol>

{

    int count; //a simple primitive type

    id *data; //Weak Type

    NSString *aString; 

//String type. *stay for pointer. all the instance object variable

//use this pointer notation

}

//property declare a class property

//nonatomic or atomic value regard the thread safety in the accessor method

//retain in the set accessor the variable value is retained

@property (nonatomic, retain) NSString aString

//this is a method interface definition

-(id)aMethod:(NSString)*paramName;

@end //end interface declaration

.m file example

#import "MyClassName.h"  //import the class interface definition file

@implementation MyClassName

@synthesize aString; 

//It tells to compiler to make automatically get/set method 

//for property aString

-(id)aMethod:(NSString)*paramName

{

    //insert here the method logic

}

@end

.java Equivalent

import ui.Class;

class MyClassName extends NSObject implements aProtocol

{

    private int count;

    private Object data;

    private String aString;

    public void setAVar(String s) { this.aString = s;}

    public String getAString (return this.aString;)

    Object aMethod (String paramName) { //logic }

}