clang API Documentation
ObjCIvarDecl - Represents an ObjC instance variable. In general, ObjC instance variables are identical to C. The only exception is Objective-C supports C++ style access control. For example:
{ id defaultToProtected; : id canBePublic; // same as C++. : id canBeProtected; // same as C++.
id canBePackage; // framework visibility (not available in C++). }