转：objective-C 的OOP(下)-类（st…

先来定义一个Human父类

定义部分：

//
//  Human.h
//  OOP
//
//  Created by jimmy.yang on 11-2-9.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Human : NSObject {
BOOL sex;
}

+(void) toString;

-(void) showSex;

@end

注：+(void)前的加号，就表示这一个是类方法(static
方法)，而-(void)表示这是一个实例方法

实现部分：

注意：下面的 -(id) init 即为构造函数。对应的，还有一个-(void)dealloc方法用来释放资源（类似于析构函数或c#中的dispose()方法）-注：dealloc方法以后在内存管理中详细学习，这里先不管它。

//
//  Human.m
//  OOP
//
//  Created by jimmy.yang on 11-2-9.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "Human.h"

@implementation Human

//构造函数
-(id) init
{
NSLog(@"init() in Human is called");
sex = TRUE;
return(self);
}

//static类方法
+ (void)toString
{
NSLog(@"this is a class method of Human");
}

//实例方法
- (void)showSex
{
NSLog(@"my sex is %@",sex?@"MALE":@"FEMALE");
}

@end

再来定义一个Woman子类

定义部分：

//
//  Woman.h
//  OOP
//
//  Created by jimmy.yang on 11-2-9.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Human.h"

@interface Woman : Human {
BOOL married;
}

-(void) canCook:(NSString*) foodName;

-(void) setMarried:(BOOL)m;

-(BOOL) Married;

@end

实现部分：

注意下面的：setMarried
与 Married 就是obj-C中属性的标准写法(当然以后还能看到其它简化的写法)

//
//  Woman.m
//  OOP
//
//  Created by jimmy.yang on 11-2-9.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "Woman.h"

@implementation Woman

//Woman类的构造函数
-(id) init{
NSLog(@"init() in Woman is called!");
if (self==[super init]){
sex = FALSE;
married = FALSE;
}
return (self);
}

//overwrite父类中的toString()
+(void)toString
{
NSLog(@"This is Woman's ToString()");
}

//Woman能做饭
-(void)canCook:(NSString*) foodName
{
NSLog(@"I can cook %@",foodName);
}

//属性的setter
-(void) setMarried:(BOOL)m
{
married = m;
}

//属性的getter
-(BOOL) Married
{
return married;
}

@end

main方法中的调用：

#import <Foundation/Foundation.h>
#import "Human.h"
#import "Woman.h"

int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

// insert code here...
NSLog(@"Hello, World!");

//调用类的“静态”方法
[Human toString];

NSLog(@"----------------");

//创造一个Human的实例
Human *man = [Human new];

//调用man的showSex方法
[man showSex];

NSLog(@"----------------");

//定义一个Woman子类的实例
Woman *wife = [Woman new];
[wife canCook:@"Rice"];

//调用继承自父类的方法
[wife showSex];

//设置属性
[wife setMarried:TRUE];

//读取属性值
NSLog(@"wife's married = %@",wife.Married==NO?@"FALSE":@"TRUE");

NSLog(@"----------------");

//调用overwrite后的toString方法
[Woman toString];

//Factory模式中常用的手法，在这里依然适用(只不过编译时会有警告 'Human' may not respond to '-canCook:')
Human *wife2 = [Woman new];
[wife2 canCook:@"soap"];

NSLog(@"----------------");

[pool drain];
return 0;
}

运行结果：

2011-02-09 17:01:02.016 OOP[1725:a0f] Hello, World!

2011-02-09 17:01:02.053 OOP[1725:a0f] this is a class method of
Human

2011-02-09 17:01:02.062 OOP[1725:a0f] ----------------

2011-02-09 17:01:02.075 OOP[1725:a0f] init() in Human is
called

2011-02-09 17:01:02.091 OOP[1725:a0f] my sex is MALE

2011-02-09 17:01:02.094 OOP[1725:a0f] ----------------

2011-02-09 17:01:02.099 OOP[1725:a0f] init() in Woman is
called!

2011-02-09 17:01:02.104 OOP[1725:a0f] init() in Human is
called

2011-02-09 17:01:02.105 OOP[1725:a0f] I can cook Rice

2011-02-09 17:01:02.108 OOP[1725:a0f] my sex is FEMALE

2011-02-09 17:01:02.109 OOP[1725:a0f] wife's married =
TRUE

2011-02-09 17:01:02.111 OOP[1725:a0f] ----------------

2011-02-09 17:01:02.116 OOP[1725:a0f] This is Woman's
ToString()

2011-02-09 17:01:02.120 OOP[1725:a0f] init() in Woman is
called!

2011-02-09 17:01:02.121 OOP[1725:a0f] init() in Human is
called

2011-02-09 17:01:02.123 OOP[1725:a0f] I can cook soap

2011-02-09 17:01:02.125 OOP[1725:a0f] ----------------