Object-c学习之路十二（OC的copy）

oc中的拷贝分为：copy(浅拷贝)和mutablecopy(深拷贝)。

浅拷贝也为指针拷贝，拷贝后原来的对象计数器会+1；

深拷贝为对象拷贝，原来的对象计数器不变。

注意：自定义对象拷贝时要实现NSCoping协议或NSMutableCopying协议.且构造方法和copyWithZone方法中最好用[self class]来代替类名

下面以NSString的拷贝 和Student,DoodStudent的copy（实现NSCoping协议）为例展示：

OC学习基本快告一段落了，终于可以见到IOS界面了呵呵呵呵。。。。。闲话少说直接上代码：

主函数：

////  main.m//  Copy////  Created by WildCat on 13-7-27.//  Copyright (c) 2013年 wildcat. All rights reserved.//#import <Foundation/Foundation.h>#import "Student.h"#import "GoodStudent.h"#pragma  mark 练习mutablecopy语法（深拷贝）对象拷贝。void mutablecopyTest(){    NSString *string =[[NSString alloc] initWithFormat:@"Age is %i",10];    //调用MutableCopy方法,产生一个可变的对象,MutableCopy后的对象和原来的对象不是同一个对象 ，原来的对象和新建的对象的计数器都是1    NSMutableString *str=[string mutableCopy];    [str appendString:@" no is 123"];    NSLog(@"String's:%@ :count is %zi,\n str's: %@: count is %zi",string,[string retainCount],str,[str retainCount]);    [str release];            [string release];}#pragma  mark copy的练习  copy是浅拷贝（指针拷贝），对象只是做了retain操作void copyTest(){    NSString *string =[[NSString alloc] initWithFormat:@"Age is %i",10];    //调用Copy方法,产生一个可变的对象,copy后的对象和原来的对象是同一个对象 ，对象的计数器都是+1    NSLog(@"Count:%zi",[string retainCount]);    NSString *str=[string copy];    NSLog(@"Count:%zi",[string retainCount]);        NSLog(@"%i",str==string);    [str release];    [string release];    }void studentNameCopy(){    Student *stu=[[[Student alloc] init] autorelease];    NSMutableString *str=[NSMutableString stringWithFormat:@"Jack"];    stu.name=str;    NSLog(@"name is :%@",stu.name);    [str appendString:@" 你好。"];    NSLog(@"name is :%@",stu.name);  //因为是用的copy方法 ，所以内容不变。如果用retain name会变    NSLog(@"str is:%@",str);}void copyStudent(){    Student *stu1=[Student studentWithName:@"lixingle"];    Student *stu2=[stu1 copy];    NSLog(@"Name1 is :%@",stu1.name);    NSLog(@"Name2 is :%@",stu2.name);    stu1.name=@"lele";    NSLog(@"Name1 is :::%@",stu1.name);    NSLog(@"Name2 is :::%@",stu2.name);    [stu2 release];    }#pragma mark GOOdStudent 的copy练习void goodStudentCopy(){    GoodStudent *good1=[GoodStudent goodStudentWithAge:10 Name:@"乐乐"];    GoodStudent *good2=[good1 copy];        //改变good1，good2不会变    good1.name=@"长超";    NSLog(@"good1: %@",good1);    NSLog(@"good2: %@",good2);    [good2 release];}int main(int argc, const char * argv[]){    @autoreleasepool {                //copyTest();        //studentNameCopy();        //copyStudent();        goodStudentCopy();            }    return 0;}

Student类（例子中父类）

#import <Foundation/Foundation.h>//对象Copy需要实现NSCoping协议@interface Student : NSObject<NSCopying>//NSString 对象一般用copy,外边的内容改变里边的内容不变。retain：当外边的内容改变时里边的内容也会改变//其他对象建议用retain@property (nonatomic,copy) NSString *name;+(id)studentWithName:(NSString *) name;-(id)copyStudent;@end

////  Student.m//  Copy////  Created by WildCat on 13-7-27.//  Copyright (c) 2013年 wildcat. All rights reserved.//#import "Student.h"@implementation Student@synthesize name=_name;+(id)studentWithName:(NSString *) name{    //这里用[self class] ,方便子类调用    Student *stu=[[[[self class] alloc] init] autorelease];    stu.name=name;    return stu;}#pragma mark 实现协议//实现协议，要实现copyWithZone 方法-(id)copyWithZone:(NSZone *)zone{    //这里创建的对象不需要释放，在外边释放   ;这里用[self class] ,方便子类调用    Student *stu=[[[self class] allocWithZone:zone] init];    stu.name=self.name;    return stu;}- (void)dealloc{    [_name release];    [super dealloc];}//重写description方法-(NSString *)description{    return [NSString stringWithFormat:@"name is %@",self.name];}@end

GoodStudent类（子类）

#import "Student.h"@interface GoodStudent : Student@property (nonatomic,assign)int age;+(id) goodStudentWithAge:(int) age Name:(NSString *)name;@end

#import "GoodStudent.h"@implementation GoodStudent+(id) goodStudentWithAge:(int) age Name:(NSString *)name{    GoodStudent *good=[GoodStudent studentWithName:name];    good.age=age;    return good;}-(id)copyWithZone:(NSZone *)zone{    GoodStudent *copy=[super copyWithZone:zone];    copy.age=self.age;    return copy;    }-(NSString *)description{    return [NSString stringWithFormat:@"name is :%@,age is:%i,",self.name,self.age];}@end