runtime.h
objc_class
typedef struct objc_method *Method;
struct objc_method {
SEL method_name OBJC2_UNAVAILABLE;
char *method_types OBJC2_UNAVAILABLE;
IMP method_imp OBJC2_UNAVAILABLE;
} OBJC2_UNAVAILABLE;
原文:http://www.cnblogs.com/feng9exe/p/7132122.html