copy And mutableCopy

copy
通过 copy 产生的对象是不可变对象（eg. NSString、NSArray、NSDictionary）
mutableCopy
通过 mutableCopy 产生的对象是可变对象（eg. NSMutableString、NSMutableArray、NSMutableDictionary）

copy 和 mutableCopy拷贝过程

• 注：深拷贝 == 内容拷贝；浅拷贝 == 指针拷贝；

自定义对象使用 copy 和 mutableCopy方法

1、必须实现 NSCopying , NSMutableCopying 协议
2、copyWithZone:方法 和 mutableCopyWithZone:方法必须实现

#import <Foundation/Foundation.h>

@interface ZQObjCopy : NSObject <NSCopying,NSMutableCopying>

@property (nonatomic,  copy) NSMutableString   *name;
@property (nonatomic,  copy) NSString          *mutableStr;
@property (nonatomic,assign) int               age;

@end

#import "ZQObjCopy.h"

@interface ZQObjCopy ()

@end

@implementation ZQObjCopy 

- (id)copyWithZone:(NSZone *)zone{
    ZQObjCopy *objCopy = [[[self class] allocWithZone:zone] init];
    
    objCopy.name = [self.name copy];
    objCopy.mutableStr = [self.mutableStr copy];
    objCopy.age = self.age;
    
    return objCopy;
}

- (id)mutableCopyWithZone:(NSZone *)zone{
    ZQObjCopy *objCopy = [[[self class] allocWithZone:zone] init];
    objCopy.name = [self.name mutableCopy];
    objCopy.mutableStr = [self.mutableStr mutableCopy];
    objCopy.age = self.age;
    
    return objCopy;
}