KVC&KVO

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KVC

1.KVC直接修改某个对象的某个属性

[stu setValue:@"MIKE" forKey:@"name"];

[stu setValue:@10 forKey:@"age"];

2.KVC也可以批量设置某个对象的所有属性

[stu setValuesForKeysWithDictionary:@{@"age": @10,@"name":@"rose"}];

3.批量获取对象的属性

NSDictionary *dict = [stu dictionaryWithValuesForKeys:@[@"name",@"age"]];

4.使用键值路径间接修改对象的属性值

stu.book = [[Book alloc] init];

[stu setValue:@1.22 forKeyPath:@"book.price"];

5.通过KeyPath来获取数组内所有对象的相同属性

NSArray *array = @[stu,stu1,stu2];

NSArray *names = [array valueForKeyPath:@"name"];

6.通过keyPath来计算所有书的价格

stu.books = @[[Book bookWithPrice:2.2],[Book bookWithPrice:2.1],[Book bookWithPrice:10]];

int sum = [[stu valueForKeyPath:@"books.@sum.price"] intValue];

所有用key的地方都可以用keyPath

=======================================KVO=======================================

KVO是监听对象属性的改变

//通过KVO来监听stu的name属性的变化

[stu addObserver:observer forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:nil];

//属性改变后，会调用监听者的方法，并把一系列参数发送过来

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

{

NSLog(@"%@",keyPath);

NSLog(@"%@",object);

NSLog(@"%@",change[@"new"]);

}