Building static C++ lib for use with Objective-c app in Xcode 4

Question

I found examples and posts to

• Create a static C++ lib for use in a C++ application
• Create a static Objective C lib for use in an Objective C app.

What I couldn't find and have hassled around with for days now, is the correct way to create a static C++ lib for use in a Objective-C app under XCode 4.

I just want to use this very simple code for testing purposes:

#include <iostream>
#include "myCppLib.h"

using namespace std;

extern "C" void show_the_world() {
    cout << "Hello, world!\n";
}

I compile this with armv6/armv7 target, GCC 4.2 compiler, Linking 'C++ Standard Library Type' as 'Static' and have "Symbols Hidden by Default" to YES, as described by the Xcode help for static C++ libs.

My Objective-C app which calls the 'show_the_world' function errors about the std++ lib, which seems not to be included or not correctly referenced:

Undefined symbols for architecture armv6:
 "std::ios_base::Init::~Init()", referenced from:
  ___tcf_0 in libmyCppLib_dev.a(myCppLib.o)
  "std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)", referenced from:
      _show_the_world in libmyCppLib_dev.a(myCppLib.o)
  "std::ios_base::Init::Init()", referenced from:
  __static_initialization_and_destruction_0(int, int)in libmyCppLib_dev.a(myCppLib.o)
  "std::cout", referenced from:
  _show_the_world in libmyCppLib_dev.a(myCppLib.o)
ld: symbol(s) not found for architecture armv6
collect2: ld returned 1 exit status

I am sure that I compiled the library for the right architecture, so there must be something wrong in another setting or with my code.

Any help is welcome!

Best regards, jimmy

Answer 1

The correct answer was provided by Jimmy Koerting in the comments: the app needs to be linked against libstdc++.dylib to resolve the standard library symbols. Thanks to Jimmy Koerting, but one more thing i want to add here is, if you are using xcode latest version with iOS 6.1 please add this libstdc++.6.dylib

Answer 2

Answered in my own comment ;)

the point was to include the std++ lib into the compiling of the resulting objective-c project, too.