首先引入电脑的基类和各个品牌的电脑类：
电脑基类：
//================== Computer.h ==================
@interface Computer : NSObject
//package to store
- (void)packaging;
@end
//================== Computer.m ==================
@implementation Computer
- (void)packaging{
//implemented by subclass
}
@end苹果电脑类 MacBookComputer：
//================== MacBookComputer.h ==================
@interface MacBookComputer : Computer
@end
//================== MacBookComputer.m ==================
@implementation MacBookComputer
- (void)packaging{
NSLog(@"MacBookComputer has been packaged");
}
@end小米电脑类 MIComputer：
//================== MIComputer.h ==================
@interface MIComputer : Computer
@end
//================== MIComputer.m ==================
@implementation MIComputer
- (void)packaging{
NSLog(@"MIComputer has been packaged");
}
@end华为电脑类 MateBookComputer：
//================== MateBookComputer.h ==================
@interface MateBookComputer : Computer
@end
//================== MateBookComputer.m ==================
@implementation MateBookComputer
- (void)packaging{
NSLog(@"MateBookComputer has been packaged");
}
@end引入电脑相关产品类以后，我们需要重新设计工厂类。因为抽象工厂方法模式的工厂是面向产品族的，所以抽象工厂方法模式里的工厂所创建的是同一产品族的产品。下面我们看一下抽象工厂方法模式的工厂该如何设计：
首先创建所有工厂都需要集成的抽象工厂，它声明了生产同一产品族的所有产品的接口：
//================== Factory.h ==================
#import "Phone.h"
#import "Computer.h"
@interface Factory : NSObject
+ (Phone *)createPhone;
+ (Computer *)createComputer;
@end
//================== Factory.m ==================
@implementation Factory
+ (Phone *)createPhone{
//implemented by subclass
return nil;
}
+ (Computer *)createComputer{
//implemented by subclass
return nil;
}
@end接着，根据不同的产品族，我们创建不同的具体工厂：
首先是苹果产品族工厂 AppleFactory：
//================== AppleFactory.h ==================
@interface AppleFactory : Factory
@end
//================== AppleFactory.m ==================
#import "IPhone.h"
#import "MacBookComputer.h"
@implementation AppleFactory
+ (Phone *)createPhone{
IPhone *iPhone = [[IPhone alloc] init];
NSLog(@"iPhone has been created");
return iPhone;
}
+ (Computer *)createComputer{
MacBookComputer *macbook = [[MacBookComputer alloc] init];
NSLog(@"Macbook has been created");
return macbook;
}
@end接着是小米产品族工厂 MIFactory：
//================== MIFactory.h ==================
@interface MIFactory : Factory
@end
//================== MIFactory.m ==================
#import "MIPhone.h"
#import "MIComputer.h"
@implementation MIFactory
+ (Phone *)createPhone{
MIPhone *miPhone = [[MIPhone alloc] init];
NSLog(@"MIPhone has been created");
return miPhone;
}
+ (Computer *)createComputer{
MIComputer *miComputer = [[MIComputer alloc] init];
NSLog(@"MIComputer has been created");
return miComputer;
}
@end最后是华为产品族工厂 HWFactory：
//================== HWFactory.h ==================
@interface HWFactory : Factory
@end
//================== HWFactory.m ==================
#import "HWPhone.h"
#import "MateBookComputer.h"
@implementation HWFactory
+ (Phone *)createPhone{
HWPhone *hwPhone = [[HWPhone alloc] init];
NSLog(@"HWPhone has been created");
return hwPhone;
}
+ (Computer *)createComputer{
MateBookComputer *hwComputer = [[MateBookComputer alloc] init];
NSLog(@"HWComputer has been created");
return hwComputer;
}
@end以上就是工厂类的设计。这样设计好之后，客户端如果需要哪一产品族的某个产品的话，只需要找到对应产品族工厂后，调用生产该产品的接口即可。假如需要苹果电脑，只需要委托苹果工厂来制造苹果电脑即可；如果需要小米手机，只需要委托小米工厂制造小米手机即可。
下面用代码来模拟一下这个场景：
//================== Using by client ==================
Store *store = [[Store alloc] init];
//Store wants to sell MacBook
Computer *macBook = [AppleFactory createComputer];
[macBook packaging];
[store sellComputer:macBook];
//Store wants to sell MIPhone
Phone *miPhone = [MIFactory createPhone];
[miPhone packaging];
[store sellPhone:miPhone];
//Store wants to sell MateBook
Computer *mateBook = [HWFactory createComputer];
[mateBook packaging];
[store sellComputer:mateBook];上面的代码就是模拟了商店售卖苹果电脑，小米手机，华为电脑的场景。而今后如果该商店引入了新品牌的产品，比如联想手机，联想电脑，那么我们只需要新增联想手机类，联想电脑类，联想工厂类即可。