1 typedef struct objc_class *Class;

 1 struct objc_class {
 2     Class isa  OBJC_ISA_AVAILABILITY;
 3 
 4 #if !__OBJC2__
 5     Class super_class                                        OBJC2_UNAVAILABLE;
 6     const char *name                                         OBJC2_UNAVAILABLE;
 7     long version                                             OBJC2_UNAVAILABLE;
 8     long info                                                OBJC2_UNAVAILABLE;
 9     long instance_size                                       OBJC2_UNAVAILABLE;
10     struct objc_ivar_list *ivars                             OBJC2_UNAVAILABLE;
11     struct objc_method_list **methodLists                    OBJC2_UNAVAILABLE;
12     struct objc_cache *cache                                 OBJC2_UNAVAILABLE;
13     struct objc_protocol_list *protocols                     OBJC2_UNAVAILABLE;
14 #endif
15 
16 } OBJC2_UNAVAILABLE;

 1 typedef struct objc_method *Method;
 2 
 3 typedef struct objc_ method {
 4 
 5     SEL method_name;
 6 
 7     char *method_types;
 8 
 9     IMP method_imp;
10 
11 };

1 const char *sel_getName(SEL sel) {
2 #ifndef NO_GC
3     if ((uintptr_t)sel == kIgnore) return "<ignored selector>";
4 #endif
5     return sel ? (const char *)sel : "<null selector>";
6 }

1 typedef id (*IMP)(id, SEL, ...)