摘要：
1. -（BOOL) isKindOfClass: <class> 判断该对象是否为<class>类或其子类的实例2. -(BOOL) isMemberOfClass: <class> 判断该对象是否为<class>类的实例3. -(BOOL) respondsToSelector: <selector> 判断该对象是否可响应<selector>函数4. +(BOOL) instancesRespondToSelector: <selector> 判断该类的实例是否可响应<selector>函数5. 阅读全文
