简单工厂是一个实体类，包含了根据不同参数直接创建对象的方法。而抽象工厂(Abstract Factory pattern)则是在简单工厂的基础上将(多个)工厂类进一步进行抽象(如UML图示)：

　　

　　在工程中，我们创建了两个实体类:动物类(Animal)和植物类(Plant)；这两个类分别遵循协议AnimalProtocol和PlantProtocol；分别有子类Dog、Fish、Bird(继承自Animal类)和Rose、Sakura(继承自Plant类)；这两个实体类分别通过工厂类AnimalFactory和PlantFactory进行实例化(均继承自BioligyFactory工厂类)；在此基础上，将工厂类进一步抽象，通过抽象工厂类AbstractFactory对工厂类进行实例化。

　　代码实现:

　　1.Animal、AnimalFactory、BiologyFactory

　　Animal、AnimalFactory代码在《》中已经创建，只需要将AnimaFactory继承于BiologyFactory并将类方法改为实例方法即可。

1 // BiologyFactory.h 2 #import 
     
       3 #import "Plant.h" 4 #import "Animal.h" 5  6 typedef NS_ENUM(NSInteger, EFactory){ 7     kAnimalFactory, 8     kPlantFactory, 9 };10 11 typedef NS_ENUM(NSInteger, EPlantType){12     kRose,13     kSakura,14 };15 16 typedef enum {17     kDog,18     kBird,19     kFish,20 }EAnimalType;21 22 @interface BiologyFactory : NSObject23 24 - (Plant*)createPlantWithType:(EPlantType)type;25 26 - (Animal*)createAnimalWithType:(EAnimalType)type;27 28 @end
     

　　2.Plant、PlantFactory

1 // Plant.h 2 #import 
     
       3  4 @protocol PlantProtocol 
      
        5 @optional 6 - (void)flower; 7 - (void)color; 8 @end 9 10 @interface Plant : NSObject
       
        11 12 @end13 14 // Rose.h15 #import "Plant.h"16 17 @interface Rose : Plant18 19 - (void)thorn;20 21 @end22 23 // Sakura.h24 #import "Plant.h"25 26 @interface Sakura : Plant27 28 - (void)enjoyFlower;29 30 @end
       
      
     

1 // PlantFactory.h 2 #import "BiologyFactory.h" 3 #import "Rose.h" 4 #import "Sakura.h" 5  6 @interface PlantFactory : BiologyFactory 7  8 - (Plant*)createPlantWithType:(EPlantType)type; 9 10 @end11 12 // PlantFactory.m13 #import "PlantFactory.h"14 15 @implementation PlantFactory16 17 - (Plant *)createPlantWithType:(EPlantType)type{18     Plant *plant = nil;19     if(type == kRose){20         plant = [Rose new];21     }else if(type == kSakura){22         plant = [Sakura new];23     }24     return plant;25 }26 27 @end

　　3.AbstractFactory创建

1 // AbstractFactory.h 2 #import 
     
       3 #import "BiologyFactory.h" 4 #import "AnimalFactory.h" 5 #import "PlantFactory.h" 6  7 @interface AbstractFactory : NSObject 8  9 + (BiologyFactory*)createFactoryWithType:(EFactory)type;10 11 @end12 13 // AbstractFactory.m14 #import "AbstractFactory.h"15 16 @implementation AbstractFactory17 18 + (BiologyFactory*)createFactoryWithType:(EFactory)type{19     BiologyFactory *factory = nil;20     if(type == kAnimalFactory){21         factory = [AnimalFactory new];22     }else if(type == kPlantFactory){23         factory = [PlantFactory new];24     }25     return factory;26 }27 28 @end