KVO KVC

@interface FoodData : NSObject

{

NSString * foodName;

float foodPrice;

}

@end

////////////////////////////////////////////////////////////////////////////

foodData = [[FoodDataalloc]init];

[foodDataaddObserver:selfforKeyPath:@"foodName"options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOldcontext:nil];

[foodDataaddObserver:selfforKeyPath:@"foodPrice"options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOldcontext:nil];

///调用

[foodDatasetValue:@"apple"forKey:@"foodName"];

[foodDatasetValue:@"100.0"forKey:@"foodPrice"];

///////响应

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

{

if( [keyPath isEqualToString:@"foodName"])

{

NSLog(@"foodName:%@",[foodDatavalueForKey:@"foodName"]);

}

else if( [keyPath isEqualToString:@"foodPrice"])

{

NSLog(@"foodPrice:%@",[foodDatavalueForKey:@"foodPrice"]);

}

}