行为型之八-状态模式

State（状态模式）

当一个对象的内在状态改变时允许改变其行为，这个对象看起来像是改变了其类。

比如AFN2.0的自定义Operation，有一个状态机转换规则，不同的状态下，有不同的属性设置。

VC.m

//HCDWork对象指定不同的状态，writeProgrem会有不同的处理结果。
HCDWork *work = [[HCDWork alloc]init];
[work writeProgram];
work.state = [[HCDAfternoonState alloc]init];
[work writeProgram];
work.state = [[HCDEventState alloc]init];
[work writeProgram];
work.state = [[HCDSleepState alloc]init];
[work writeProgram];

HCDState.h

@protocol HCDState <NSObject>
-(void)writeProgram:(HCDWork *)work;
@end

HCDWork.h

@interface HCDWork : NSObject
@property(nonatomic,strong)id<HCDState> state;
@property(nonatomic,assign)CGFloat hour;
@property(nonatomic,assign)BOOL finished;
-(void)writeProgram;
@end

HCDWork.m

@implementation HCDWork
-(instancetype)init{
    self = [super init];
    if (self) {
        self.state = [[HCDForenoonState alloc]init];
    }
    return self;
}

-(void)writeProgram{
    [self.state writeProgram:self];
}
@end

HCDAfternoonState.h

@interface HCDAfternoonState : NSObject<HCDState>

@end

HCDAfternoonState.m

@implementation HCDAfternoonState
-(void)writeProgram:(HCDWork *)work{
    if (work.hour < 17) {
        NSLog(@"当前时间：{%.f}点，下午状态还不错，继续努力", work.hour);
    } else {
        work.state = [[HCDEventState alloc] init];
        [work writeProgram];
    }
}
@end

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