结构型之四-装饰模式

Decrator（装饰模式）

动态的给一个对象添加一些额外的职责，就增加功能来说，装饰模式比生成子类更加灵活。decorate应该像礼物一样层层封装，每一层都添加新的功能。

VC.m

- (void)viewDidLoad {
    [super viewDidLoad];
    //原始对象
    ConcreteComponent *component = [[ConcreteComponent alloc]init];
    //装饰对象
    ConcreteDecoratorA *decoratorA = [[ConcreteDecoratorA alloc]init];
    ConcreteDecoratorB *decoratorB = [[ConcreteDecoratorB alloc]init];
    
    //装饰对象指定原始对象，后面就是用装饰对象。这样既有原始对象的功能，也有装饰对象的功能。
    decoratorA.component = component;
    decoratorB.component = component;
    
    [decoratorA operation];
    [decoratorB operation];
}

Decorator.h // 装饰类

@interface Decorator : Component
//装饰对象需要装饰的原始对象
@property(nonatomic, strong)Component *component;
@end

Decorator.m

@implementation Decorator
-(void)operation{
    if (self.component) {
        [self.component operation];
    }
}
@end

ConcreteDecoratorA.h // 装饰者A

@interface ConcreteDecoratorA : Decorator
@end

ConcreteDecoratorA.m

@implementation ConcreteDecoratorA

-(void)operation{
    [super operation];
    [self addedBehavior]; // 添加的装饰功能
}
- (void)addedBehavior{
    NSLog(@"ConcreteDecoratorA添加的装饰功能，相当于对Component进行装饰");
}
@end

设计图