IOS开发之KVC与KVO简述_移动开发_编程开发_程序员俱乐部

KVC:Key-Value Coding

KVO:Key-Value Observing

Person.m

@interface Person : NSObject{
    //该访问修饰符用于说明即使私有成员变量也可以通过kvc方式访问和赋值
    @private
    NSString *_name;
}
@end

@implementation Person
@end

PersonObserve.m

@interface PersonObserve : NSObject
@end

@implementation PersonObserve
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    Person *p = (Person *)object;
    //使用kvc方式获取成员变量keypath的值
    NSLog(@"%@",[p valueForKey:keyPath]);
}
@end

main.m

int main(int argc, const char * argv[]) {
    //观察者类
    PersonObserve *po = [[PersonObserve alloc] init];
    Person *p = [[Person alloc] init];
    //使用kvo方式对成员变量“name”的属性值变化增加观察者po
    //po将在该属性值发生变化时执行- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context方法
    [p addObserver:po forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:nil];
    
    //通过kvc方式设置成员变量“name”的属性值
    //出发观察者执行对应方法
    [p setValue:@"yangys" forKey:@"name"];
    
    //移除对私有成员变量“name”的观察
    [p removeObserver:po forKeyPath:@"name"];
    return 0;
}

结果：

2015-03-02 20:57:52.487 KVC&KOC[843:24874] yangys
Program ended with exit code: 0