KVC 监听某对象属性值的改变

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原创最新推荐文章于 2026-05-06 10:19:34 发布 741 阅读 AI 写同款· GEO 优化 ›

一种车内UWB圆极化天线的理论推导及具体实现本文详细描述了一款工作于UWB channel 9也即中心频率为7987.2MHz,带宽为499.2MHz的圆极化天线。首先是理论推导圆极化天线的物理尺寸参数，分析物理尺寸参数对天线性能指标的影响。然后分析圆极化天线在汽车驾驶室这种狭窄空间应用中带来的优势，也即可以最大化的极化损失多径，提高主径接收信号的信噪比。阅读详情

//被监控的类 @interface Person : NSObject{ NSString *name; } @property(retain) NSString *name; //被监控的属性 @end @implementation Person @synthesize name; @end //观察者 @interface KVCObserver : NSObject {} @end @implementation KVCObserver //callback - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{ NSLog(@"value change! key path :%@",keyPath); NSLog(@"object : %@",object); NSLog(@"old value: %@",[change objectForKey: NSKeyValueChangeOldKey ]); NSLog(@"new value: %@",[change objectForKey: NSKeyValueChangeNewKey ]); } @end KVCObserver *vc = [[VCObserver alloc] init]; Person *friend = [[Person alloc] init]; friend.name = @"jack"; [friend addObserver:vc forKeyPath:@"name" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:nil]; [friend setName:@"jory"]; //执行后将call 到vc

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