title: Xcode 4 FLTK 1.3.0 undefined architecture x86_64
body: <blockquote>
    <blockquote>
      <blockquote>
        <p>Hi, I am using Xcode 4 and trying to set up FLTK 1.3.0 to run Bjarne
        Stroustrup's Chapter 12 FLTK Demo at the end of the chapter. I keep
        getting the following error when compiling, and have no idea where to go.
        I have an idea it might have to do with the linker flags, but I don't know
        what flag to add and where...</p>
        
        <p>Here's the error:</p>
        
        <p>Undefined symbols for architecture x86_64:
           "Fl_JPEG_Image::Fl_JPEG_Image(char const*)", referenced from:
               Graph_lib::Image::Image(Point, String,
        Graph_lib::Suffix::Encoding) in Graph.o
           "Fl_GIF_Image::Fl_GIF_Image(char const*)", referenced from:
               Graph_lib::Image::Image(Point, String,
        Graph_lib::Suffix::Encoding) in Graph.o
        ld: symbol(s) not found for architecture x86_64
        clang: error: linker command failed with exit code 1 (use -v to see
        invocation)</p>
      </blockquote>
    </blockquote>
  </blockquote>