isKindOfClass:和isMemberOfClass:-b

isKindOfClass:

Returns a Boolean value that indicates whether the receiver is an instance of given class or an instance of any class that inherits from that class. (required)

isKindOfClass能确定一个对象是否是一个类的成员，或者是派生自该类的成员

isMemberOfClass:

Returns a Boolean value that indicates whether the receiver is an instance of a given class. (required)

isMemberOfClass只能确定一个对象是否是一个类的成员

例如：

[[NSMutableData data] isKindOfClass:[NSData class]];      // YES

[[NSMutableData data] isMemberOfClass:[NSData class]]; // NO