Objective-C Runtime: best way to check if class conforms to protocol?

I have a Class (but no instance) and need to know if it conforms to a certain protocol. However, Class can be subclassed several times and class_conformsToProtocol() ignores protocols declared on superclasses. I could just use class_getSuperclass() and recursively check all the classes in the hierarchy upwards until the superclass is nil. However I wonder if that might be inefficient for deeply nested class hierarchies, and maybe there's a nicer way to do that? In other words, how is the NSObject method conformsToProtocol best implemented using Objective-C runtime methods so that it finds protocols on superclasses? ``` [myObject conformsToProtocol:@protocol(MyProtocol)]; ``` If I'm on the right track with recursively going up the class hierarchy just let me know.