Objective-C 的OOP(下)-类（static）方法、实例方法、overwrite（覆写）、属性（property）

先来定义一个Human父类

定义部分：

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// // 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.

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// // 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：

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// // 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)

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// // 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：

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#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] —————-