第08天OC语言(20):自定义类实现Copy

• 不要等到明天，明天太遥远，今天就行动。

须读:看完该文章你能做什么？

一个类如何实现自定义copy,以及注意事项

学习前:你必须会什么?（在这里我已经默认你具备C语言的基础了）

什么类,copy的本质是什么

---

一、本章笔记

 一、自定义类实现copy
    1.遵循两个协议 <NSCopying,NSMutableCopying>
    2.实现copyWithZone、mutableCopyWithZone方法
    3.样式
         - (id)copyWithZone:(NSZone *)zone
         {
             Person *p = [[self class] allocWithZone:zone];
             p.age = _age;
             p.name = _name;
             return p;
         }
        子类
         - (id)copyWithZone:(NSZone *)zone
         {
         id obj = [[self class] allocWithZone:zone];
         id obj = [super copyWithZone:zone];
         [obj setHeight:_height];
         // 3.返回副本
         return obj;
         }

二、code

main.m

#pragma mark 20-自定义类实现Copy
#pragma mark 概念
/*
 一、自定义类实现copy
    1.遵循两个协议 <NSCopying,NSMutableCopying>
    2.实现copyWithZone、mutableCopyWithZone方法
    3.样式
         - (id)copyWithZone:(NSZone *)zone
         {
             Person *p = [[self class] allocWithZone:zone];
             p.age = _age;
             p.name = _name;
             return p;
         }
        子类
         - (id)copyWithZone:(NSZone *)zone
         {
         id obj = [[self class] allocWithZone:zone];
         id obj = [super copyWithZone:zone];
         [obj setHeight:_height];
         // 3.返回副本
         return obj;
         }

 */
#pragma mark - 代码
#import <Foundation/Foundation.h>
#pragma mark 类
#import "Person.h"
#import "Student.h"
#pragma mark - main函数
int main(int argc, const char * argv[])
{
    
#pragma 1.
    
    // 1.以后想让自定义的对象 能够被copy只需要遵守 <NSCopying> 协议
    // 2.实现协议中的  - (id)copyWithZone:(NSZone *)zone
    // 3.在 - (id)copyWithZone:(NSZone *)zone 创建一个副本对象,然后将当前对象的值 赋值给副本对象即可
    

    Person *p = [[Person alloc]init];
    p.age = 25;
    p.name = @"lyh";
    NSLog(@"%@",p);

    /*
     reason: '-[Person copyWithZone:]: unrecognized selector sent to instance 0x100204ac0'
     *** First throw call stack:
     
      reason: '-[Person mutableCopyWithZone:]: unrecognized selector sent to instance 0x1001025e0'
     */
//    Person *p2 = [p copy];
    Person *p2 = [p mutableCopy];
    NSLog(@"%@",p2);
    
    Student *s = [[Student alloc]init];
    s.age = 11;
    s.name = @"lll";
    s.height = 1.33;
    NSLog(@"%@",s);
    
    // 如果想让子类在copy的时候 保留子类的属性,那么必须重写copyWithZone方法,在该方法中先调用父类创建副本设置值,然后再设置子类特有的值
    Student *s2 = [s copy];
    NSLog(@"%@",s2);
    

    return 0;
}

Person

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

@interface Person : NSObject<NSCopying,NSMutableCopying>
@property (nonatomic,assign) int age;
@property (nonatomic,copy) NSString *name;
@end

>>>.m
#import "Person.h"

@implementation Person

- (id)copyWithZone:(NSZone *)zone
{
    // 1.创建一个新的对象
    Person *p = [[self class] allocWithZone:zone];
    
    // 2.设置当前对象的内容 给新的对象
    p.age = _age;
    p.name = _name;
    
    // 3.返回新的对象
    return p;
}

- (id)mutableCopyWithZone:(NSZone *)zone
{
    // 1.创建一个新的对象
    Person *p = [[self class] allocWithZone:zone];
    
    // 2.设置当前对象的内容 给新的对象
    p.age = _age;
    p.name = _name;
    
    // 3.返回新的对象
    return p;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"name = %@, age = %i",_name,_age];
}

@end

Person

>>>.h
#import "Person.h"

@interface Student : Person

@property (nonatomic,assign) double height;

@end
>>>.m
#import "Student.h"

@implementation Student

- (id)copyWithZone:(NSZone *)zone
{
    // 1.创建副本
//    id obj = [[self class] allocWithZone:zone];
//    // 2.设置数据给副本
//    [obj setAge:[self age]];
//    [obj setName:[self name]];
    id obj = [super copyWithZone:zone];
    [obj setHeight:_height];
    // 3.返回副本
    return obj;
}


- (NSString *)description
{
    return [NSString stringWithFormat:@"name = %@, age = %i,height = %f",[self name],[self age],_height];
}

@end