OC-觀察者練習練習

main.h


    //被觀察的對象
    Jones *joens = [[Jones alloc] initWithJones];
    
    //觀察的對象
    Lucy *lucy = [[Lucy alloc] initWithLucy:joens];
    

    [[NSRunLoop currentRunLoop] run];


@interface Jones : NSObject

@property(nonatomic,assign) int happy;

-(instancetype)initWithJones;

//高興值增加
-(void)happyIncrement;

————————————————————————————————

@implementation Jones

//高興值
-(void)happyIncrement
{
    //通過KVC才能觸發KVO
    
    NSNumber *number = [NSNumber numberWithInt:++_happy];
    //[self setHappy:++_happy];
    
    [self setValue:number forKey:@"happy"];
    
    //[self setHappy:12]
    
    NSLog(@"%d",self->_happy);

};

-(instancetype)initWithJones
{
    if(self = [super init])
    {
        [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(happyIncrement) userInfo:nil repeats:YES];
    }
    return self;
}


@implementation Jones

//高興值
-(void)happyIncrement
{
    //通過KVC才能觸發KVO
    
    NSNumber *number = [NSNumber numberWithInt:++_happy];
    //[self setHappy:++_happy];
    
    [self setValue:number forKey:@"happy"];
    
    //[self setHappy:12]
    
    NSLog(@"%d",self->_happy);

};

-(instancetype)initWithJones
{
    if(self = [super init])
    {
        [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(happyIncrement) userInfo:nil repeats:YES];
    }
    return self;
}

@implementation Lucy
-(instancetype)initWithLucy:(Jones *)jones
{
    if (self = [super init])
    {
        //當Jones傳入進來 我們就對他觀察
        
        self->_jones = jones;
        
        self->_jones.happy = 0;
        
        //添加觀察者模式
        /*
            參數介紹 1,觀察那個對象 2,觀察那個屬性 3,新值,和舊值 4,可以隨便給
         
        */
        [_jones addObserver:self forKeyPath:@"happy" options:NSKeyValueObservingOptionOld|NSKeyValueObservingOptionNew context:nil];
    };

    return self;
}


//如果被觀察者的對象屬性被改變這個對象就回被觸發!
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    /**
        1.參數介紹
            1.keyPath 那個屬性
            2.object  那個對象
            3.change  屬性大全
    **/
    
    //如果被監聽屬性加到10了 移除被觀察的對象
    if ([[change objectForKey:@"new"] intValue] == 10)
    {
        //移除觀察者對象   
        [_jones removeObserver:self forKeyPath:@"happy"];
    }
    
    //否則打贏屬性
    NSLog(@"觀察者調用了->%@",[change objectForKey:@"new"]);
    
};