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