Key-Value coding (KVC)

 

KVC定义在NSkeyvalueCoding协议里,这个协议是NSObject的一个类别,所以所有NSObject的子类都可以调用这个协议.

要正确使用KVC必需遵循COCOA的一下惯例.

1,要给一个key付值,这个 key 必需要定义在 类里

 

 

 

@interface NSObject (NS<a href="/tag/keyv/" target="_blank" class="keywords">keyv</a>alueCoding) - (void) setValue: (id)anObject forKey: (N<a href="/tag/sst/" target="_blank" class="keywords">sst</a>ring*)aKey; - (void) setValue: (id)anObject forKeyPath: (N<a href="/tag/sst/" target="_blank" class="keywords">sst</a>ring*)aKey; - (id) valueForKey: (N<a href="/tag/sst/" target="_blank" class="keywords">sst</a>ring*)aKey; - (id) valueForKeyPath: (N<a href="/tag/sst/" target="_blank" class="keywords">sst</a>ring*)aKey; @end Person *a = [[Person alloc] initWithName:@"Leon"]; Person *b = [[Person alloc] initWithName:@"Peng"]; [a setValue:b forKey:@"alils"]; [b setValue:a forKey:@"alils"]; Person *c = [[a valueForKey:@"alils"] retain]; NSLog(@"c %@",[c name]); NSLog(@"class %@",[c className]); [c release]; [a release]; [b release];