自定义实体类的深拷贝实现与应用-优快云博客

用一句简单的话来说就是：浅拷贝只是对指针的拷贝，拷贝后两个指针指向同一个内存空间；深拷贝不但对指针进行拷贝，而且对指针指向的内容进行拷贝，经深拷贝后的指针是指向两个不同地址的指针。系统默认的浅拷贝。想要实现深拷贝需要自己遵守NSCopying协议和NSMutableCopying协议并且重写方法。

用demo来演示一下：

自定义实体类（一）

NSString *aName=[[NSString alloc] initWithString:@"Tom"];

NSString *aEmail=[[NSString alloc] initWithString:@"Tom@yahoo.cn"];

int aSalary=1000;

自定义实体类（二）

NSString *bName=[[NSString alloc] initWithString:@"LiLei"];

NSString *bEmail=[[NSString alloc] initWithString:@"LiLei@yahoo.cn"];

int bSalary=1500;

AddressCard *card1=[[AddressCard alloc] init];

AddressCard *card2=[[AddressCard alloc] init];

[card1 setName:aName andEmail:aEmail andSalary:aSalary];

[card2 setName:bName andEmail:bEmail andSalary:bSalary];

NSMutableArray *objArray=[NSMutableArray arrayWithObjects:

card1,

card2,

nil];

NSMutableArray *objArray2=[objArray mutableCopy];

// 输出objArray

NSLog(@"objArray: ");

for (AddressCard *theCard in objArray) {

[theCard print];

}

2012-12-07 23:06:37.708 DemoVideo[699:1b803] objArray:

2012-12-07 23:06:37.709 DemoVideo[699:1b803] =====================

2012-12-07 23:06:37.709 DemoVideo[699:1b803] name=Tom

2012-12-07 23:06:37.709 DemoVideo[699:1b803] email=Tom@yahoo.cn

2012-12-07 23:06:37.709 DemoVideo[699:1b803] =====================

2012-12-07 23:06:37.710 DemoVideo[699:1b803] =====================

2012-12-07 23:06:37.710 DemoVideo[699:1b803] name=LiLei

2012-12-07 23:06:37.710 DemoVideo[699:1b803] email=LiLei@yahoo.cn

2012-12-07 23:06:37.711 DemoVideo[699:1b803] =====================

// 输出objArray2

NSLog(@"objArray2: ");

for (AddressCard *theCard in objArray2) {

[theCard print];

}

2012-12-07 23:07:36.547 DemoVideo[699:1b803] objArray2:

2012-12-07 23:07:36.547 DemoVideo[699:1b803] =====================

2012-12-07 23:07:36.547 DemoVideo[699:1b803] name=Tom

2012-12-07 23:07:36.548 DemoVideo[699:1b803] email=Tom@yahoo.cn

2012-12-07 23:07:36.548 DemoVideo[699:1b803] =====================

2012-12-07 23:07:36.548 DemoVideo[699:1b803] name=LiLei

2012-12-07 23:07:36.549 DemoVideo[699:1b803] email=LiLei@yahoo.cn

2012-12-07 23:07:36.549 DemoVideo[699:1b803] =====================

// 改变card1的值

AddressCard *tempCard=[objArray objectAtIndex:0];

tempCard.name=@"CarBoon";

tempCard.email=@"CarBoon@yahoo.cn";

[tempCard print];

2012-12-07 23:07:50.844 DemoVideo[699:1b803] =====================

2012-12-07 23:07:50.844 DemoVideo[699:1b803] name=CarBoon

2012-12-07 23:07:50.844 DemoVideo[699:1b803] email=CarBoon@yahoo.cn

2012-12-07 23:07:50.845 DemoVideo[699:1b803] =====================

此时输出以下内容时请注意红色高亮部分的变化

// 输出objArray

NSLog(@"objArray: ");

for (AddressCard *theCard in objArray) {

[theCard print];

}

2012-12-07 23:08:14.460 DemoVideo[699:1b803] objArray:

2012-12-07 23:08:14.460 DemoVideo[699:1b803] =====================

2012-12-07 23:08:14.461 DemoVideo[699:1b803] name=CarBoon

2012-12-07 23:08:14.461 DemoVideo[699:1b803] email=CarBoon@yahoo.cn

2012-12-07 23:08:14.461 DemoVideo[699:1b803] =====================

2012-12-07 23:08:14.461 DemoVideo[699:1b803] name=LiLei

2012-12-07 23:08:14.462 DemoVideo[699:1b803] email=LiLei@yahoo.cn

2012-12-07 23:08:14.462 DemoVideo[699:1b803] =====================

// 输出objArray2

NSLog(@"objArray2: ");

for (AddressCard *theCard in objArray2) {

[theCard print];

}

2012-12-07 23:08:44.689 DemoVideo[699:1b803] objArray2:

2012-12-07 23:08:45.493 DemoVideo[699:1b803] =====================

2012-12-07 23:08:45.493 DemoVideo[699:1b803] name=CarBoon

2012-12-07 23:08:45.493 DemoVideo[699:1b803] email=CarBoon@yahoo.cn

2012-12-07 23:08:45.493 DemoVideo[699:1b803] =====================

2012-12-07 23:08:46.021 DemoVideo[699:1b803] =====================

2012-12-07 23:08:46.021 DemoVideo[699:1b803] name=LiLei

2012-12-07 23:08:46.021 DemoVideo[699:1b803] email=LiLei@yahoo.cn

2012-12-07 23:08:46.021 DemoVideo[699:1b803] =====================

下面，我们来讲解，为自己创建的类实现拷贝！（深拷贝）

主要用到自己定义的类。因为默认，自己定义的类没有实现NSCopying协议和NSMutableCopying协议。

NSCopying协议：

- (id)copyWithZone:(NSZone *)zone;

NSMutableCopying协议

- (id)mutableCopyWithZone:(NSZone *)zone;

分别用来实现不可变对象的拷贝和可变对象的拷贝。

要实现自己类的拷贝，就要实现响应的协议，并且重写协议的响应方法。

代码如下：

在*.h中申明协议：

@interface AddressCard : NSObject<</span>NSCopying,NSMutableCopying>

在*.m中实现协议：

#pragma mark- NSCopying

- (id)copyWithZone:(NSZone *)zone{

AddressCard *newCard=[[self class] allocWithZone:zone];

newCard.name=_name;

newCard.email=_email;

newCard.salary=salary;

return newCard;

}

#pragma mark- NSMutableCopying

- (id)mutableCopyWithZone:(NSZone *)zone{

AddressCard *newCard=[[self class] allocWithZone:zone];

//[newCard setName:_name andEmail:_email andSalary:salary];

newCard.name=_name;

newCard.email=_email;

newCard.salary=salary;

return newCard;

}

使用时：

AddressCard *cloneCard=[card1 copy];

[cloneCard print];

2012-12-08 22:31:06.206 DemoVideo[464:1b803] =====================

2012-12-08 22:31:06.207 DemoVideo[464:1b803] name=Tom

2012-12-08 22:31:06.207 DemoVideo[464:1b803] email=Tom@yahoo.cn

2012-12-08 22:31:06.207 DemoVideo[464:1b803] =====================

card1.name=@"changeValue";

card1.email=@"changeValue@yahoo.cn";

[card1 print];

2012-12-08 22:31:06.207 DemoVideo[464:1b803] =====================

2012-12-08 22:31:06.207 DemoVideo[464:1b803] name=changeValue

2012-12-08 22:31:06.207 DemoVideo[464:1b803] email=changeValue@yahoo.cn

2012-12-08 22:31:06.208 DemoVideo[464:1b803] =====================

[cloneCard print];

2012-12-08 22:31:22.731 DemoVideo[464:1b803] =====================

2012-12-08 22:31:22.731 DemoVideo[464:1b803] name=Tom

2012-12-08 22:31:22.731 DemoVideo[464:1b803] email=Tom@yahoo.cn

2012-12-08 22:31:22.731 DemoVideo[464:1b803] =====================

从输出可见，card1和cloneCard占有不同的内存空间！

深拷贝浅拷贝的区别