首先我们定义手机这个类，它有几个属性：
//================== Phone.h ==================
@interface Phone : NSObject
@property (nonatomic, copy) NSString *cpu;
@property (nonatomic, copy) NSString *capacity;
@property (nonatomic, copy) NSString *display;
@property (nonatomic, copy) NSString *camera;
@end然后我们创建抽象builder类：
//================== Builder.h ==================
#import "Phone.h"
@interface Builder : NSObject
{
@protected Phone *_phone;
}
- (void)createPhone;
- (void)buildCPU;
- (void)buildCapacity;
- (void)buildDisplay;
- (void)buildCamera;
- (Phone *)obtainPhone;
@end抽象builder类声明了创建手机各个组件的接口，也提供了返回手机实例的对象。
接下来我们创建对应不同手机的具体生成者类：
IPhoneXR手机的builder：IPhoneXRBuilder：
//================== IPhoneXRBuilder.h ==================
@interface IPhoneXRBuilder : Builder
@end
//================== IPhoneXRBuilder.m ==================
@implementation IPhoneXRBuilder
- (void)createPhone{
_phone = [[Phone alloc] init];
}
- (void)buildCPU{
[_phone setCpu:@"A12"];
}
- (void)buildCapacity{
[_phone setCapacity:@"256"];
}
- (void)buildDisplay{
[_phone setDisplay:@"6.1"];
}
- (void)buildCamera{
[_phone setCamera:@"12MP"];
}
- (Phone *)obtainPhone{
return _phone;
}
@end小米8手机的builder：MI8Builder：
//================== MI8Builder.h ==================
@interface MI8Builder : Builder
@end
//================== MI8Builder.m ==================
@implementation MI8Builder
- (void)createPhone{
_phone = [[Phone alloc] init];
}
- (void)buildCPU{
[_phone setCpu:@"Snapdragon 845"];
}
- (void)buildCapacity{
[_phone setCapacity:@"128"];
}
- (void)buildDisplay{
[_phone setDisplay:@"6.21"];
}
- (void)buildCamera{
[_phone setCamera:@"12MP"];
}
- (Phone *)obtainPhone{
return _phone;
}
@end从上面两个具体builder的代码可以看出，这两个builder都按照其对应的手机配置来创建其对应的手机。
下面来看一下Director的用法：
//================== Director.h ==================
#import "Builder.h"
@interface Director : NSObject
- (void)constructPhoneWithBuilder:(Builder *)builder;
- (Phone *)obtainPhone;
@end
//================== Director.m ==================
implementation Director
{
Builder *_builder;
}
- (void)constructPhoneWithBuilder:(Builder *)builder{
_builder = builder;
[_builder buildCPU];
[_builder buildCapacity];
[_builder buildDisplay];
[_builder buildCamera];
}
- (Phone *)obtainPhone{
return [_builder obtainPhone];
}
@end
Director类提供了
construct:方法，需要传入builder的实例。该方法里面按照既定的顺序来创建手机。
最后我们看一下客户端是如何使用具体的Builder和Director实例的：
//================== Using by client ==================
//Get iPhoneXR
//1. A director instance
Director *director = [[Director alloc] init];
//2. A builder instance
IPhoneXRBuilder *iphoneXRBuilder = [[IPhoneXRBuilder alloc] init];
//3. Construct phone by director
[director construct:iphoneXRBuilder];
//4. Get phone by builder
Phone *iPhoneXR = [iphoneXRBuilder obtainPhone];
NSLog(@"Get new phone iPhoneXR of data: %@",iPhoneXR);
//Get MI8
MI8Builder *mi8Builder = [[MI8Builder alloc] init];
[director construct:mi8Builder];
Phone *mi8 = [mi8Builder obtainPhone];
NSLog(@"Get new phone MI8 of data: %@",mi8);从上面可以看出客户端获取具体产品的过程：
- 首先需要实例化一个Director的实例。
- 然后根据所需要的产品找出其对应的builder。
- 将builder传入director实例的
construct:方法。- 从builder的
obtainPhone获取手机实例。