IOS開發之KVC與KVO簡述，ioskvckvo

IOS開發之KVC與KVO簡述，ioskvckvo

KVC:Key-Value Coding

KVO:Key-Value Observing

 

Person.m

@interface Person : NSObject{    //該存取修飾詞用於說明即使私人成員變數也可以通過kvc方式訪問和賦值    @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方式擷取成員變數keypath的值    NSLog(@"%@",[p valueForKey:keyPath]);}@end

main.m

int main(int argc, const char * argv[]) {    //觀察者類    PersonObserve *po = [[PersonObserve alloc] init];    Person *p = [[Person alloc] init];    //使用kvo方式對成員變數“name”的屬性值變化增加觀察者po    //po將在該屬性值發生變化時執行- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context方法    [p addObserver:po forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:nil];        //通過kvc方式設定成員變數“name”的屬性值    //出發觀察者執行對應方法    [p setValue:@"yangys" forKey:@"name"];        //移除對私人成員變數“name”的觀察    [p removeObserver:po forKeyPath:@"name"];    return 0;}

結果：

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