Decrator（裝飾模式）

動(dòng)態(tài)的給一個(gè)對象添加一些額外的職責(zé)，就增加功能來說，裝飾模式比生成子類更加靈活。decorate應(yīng)該像禮物一樣層層封裝，每一層都添加新的功能。

VC.m

- (void)viewDidLoad {
    [super viewDidLoad];
    //原始對象
    ConcreteComponent *component = [[ConcreteComponent alloc]init];
    //裝飾對象
    ConcreteDecoratorA *decoratorA = [[ConcreteDecoratorA alloc]init];
    ConcreteDecoratorB *decoratorB = [[ConcreteDecoratorB alloc]init];
    
    //裝飾對象指定原始對象，后面就是用裝飾對象。這樣既有原始對象的功能，也有裝飾對象的功能。
    decoratorA.component = component;
    decoratorB.component = component;
    
    [decoratorA operation];
    [decoratorB operation];
}

Decorator.h // 裝飾類

@interface Decorator : Component
//裝飾對象需要裝飾的原始對象
@property(nonatomic, strong)Component *component;
@end

Decorator.m

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

ConcreteDecoratorA.h // 裝飾者A

@interface ConcreteDecoratorA : Decorator
@end

ConcreteDecoratorA.m

@implementation ConcreteDecoratorA

-(void)operation{
    [super operation];
    [self addedBehavior]; // 添加的裝飾功能
}
- (void)addedBehavior{
    NSLog(@"ConcreteDecoratorA添加的裝飾功能，相當(dāng)于對Component進(jìn)行裝飾");
}
@end

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