How do I invoke xgettext from xcode

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C++

localization

Xcode

GNU

I am implementing i18n to my project in c++ using GNU xgettext, Xcode.

The situation is as follows

FileOne.cpp

 void somefunction()
 { 
     string file = "fileName";
     loggerClass.addlog(gettext_args("some %s missing ", file));
 }
FileTwo.cpp

 void someOtherfunction()
 { 
     string doc = "docName";
     loggerClass.addlog(gettext_args("some %s missing ", doc));
 }
FileThree.cpp

std::string gettext_args()
{
    gettextWithArgs(const std::string& format, Args ...args);
    return string_format(gettext(format.c_str(), args…));
}

Since each file do not have explicit gettext() function call, I could not invoke xgettext for individual files (like: xgettext -d FileOne -o FileOne.pot FileOne.cpp) for this situation.

How should I invoke xgettext for a whole project (probably from Xcode)?

Thanks