////  main.m//  自定义类实现copy#import 
     
      #import "Person.h"#import "Student.h"int main(int argc, const char * argv[]) {    /*     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方法中创建一个副本对象, 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 =  30;    p.name = @"lnj";    NSLog(@"%@", p);    Person *p22 = [p copy];//p没有copy方法，    Person *p2 = [p mutableCopy];    NSLog(@"%@", p2);//name= lnj, age = 30    NSLog(@"%@", p22);//name = lnj, age = 30    p.age = 100;    p.name = @"ssss";    NSLog(@"%@", p2);//name= lnj, age = 30    NSLog(@"%@", p22);//name = lnj, age = 30                Student *stu = [[Student alloc] init];    stu.age = 30;    stu.height = 1.75;    stu.name = @"lnj";    NSLog(@"stu = %@", stu);    // 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 *stu2 = [stu copy];    NSLog(@"stu2 = %@", stu2);        return 0;}
     

////  Person.h#import 
     
      @interface Person : NSObject
      
         //才有copy方法，@property (nonatomic, assign) int age;@property (nonatomic, copy) NSString *name;@end
      
     

////  Person.m#import "Person.h"@implementation Person- (id)copyWithZone:(NSZone *)zone  //拷贝一个副本{    // 1.创建一个新的对象    Person *p = [[[self class] allocWithZone:zone] init];  //class方法，获取这个对象对应的类。    // 2.设置当前对象的内容给新的对象，拷贝的对象和原来对象的内容要一样，    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] init];    // 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

////  Student.h//#import "Person.h"@interface Student : Person  //子类继承父类，会继承父类的协议。@property (nonatomic, assign) double height;@end

////  Student.m#import "Student.h"@implementation Student- (id)copyWithZone:(NSZone *)zone{    // 1.创建副本    // id obj = [[self class] allocWithZone:zone];    id obj = [super copyWithZone:zone];    // 2.设置数据给副本//    [obj setAge:[self age]];//    [obj setName:[self name]];    [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