Some corefoundation wrappers, Implement Associate and Unassociate for mac mime types

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@33732 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/mac/corefoundation/cfstring.h

@@ -9,6 +9,9 @@
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
+#ifndef __WX_CFSTRINGHOLDER_H__
+#define __WX_CFSTRINGHOLDER_H__
+
 #ifdef __DARWIN__
     #include <CoreFoundation/CFString.h>
 #else
@@ -70,7 +73,7 @@ public:
 
     void Assign( const wxString &str , wxFontEncoding encoding ) ;
 
-    operator CFStringRef () { return m_cfs; }
+    operator CFStringRef () const { return m_cfs; }
     wxString AsString( wxFontEncoding encoding = wxFONTENCODING_DEFAULT ) ;
 
 private:
@@ -81,3 +84,4 @@ private:
     DECLARE_NO_COPY_CLASS( wxMacCFStringHolder )
 } ;
 
+#endif //__WXCFSTRINGHOLDER_H__