Linking libraries OpenCV 2.4.2 on xcode 4.5.1

Question

I have installed opencv with macports following the directions here: Compile OpenCV (2.3.1+) for OS X Lion / Mountain Lion with Xcode

I have also search and tried every other variation of this on stackexchange and google, but this seems to get me closest.

It seems to work for some things, but not for sample code that ships with 2.4.2. Note that I have added ALL opencv 2.4.2 dylibs Link Binary with Libraries.

For example, the following will compile and run:

#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>

int main ( int argc, char **argv )
{
    cvNamedWindow( "My Window", 1 );
    IplImage *img = cvCreateImage( cvSize( 640, 480 ), IPL_DEPTH_8U, 1 );
    CvFont font;
    double hScale = 1.0;
    double vScale = 1.0;
    int lineWidth = 1;
    cvInitFont( &font, CV_FONT_HERSHEY_SIMPLEX | CV_FONT_ITALIC,
           hScale, vScale, 0, lineWidth );
    cvPutText( img, "Hello World!", cvPoint( 200, 400 ), &font,
          cvScalar( 255, 255, 0 ) );
    cvShowImage( "My Window", img );
    cvWaitKey();
    return 0;
}

However, when I try to build any of the samples, such as the display_image.cpp, example, as follows, I get link errors.

-DOES NOT WORK-

 #include <stdio.h>
 #include <iostream>
 #include "opencv2/imgproc/imgproc.hpp"
 #include "opencv2/highgui/highgui.hpp"
 #include "opencv2/flann/miniflann.hpp"

 using namespace cv; // all the new API is put into "cv" namespace. Export its content
 using namespace std;
 using namespace cv::flann;

static void help()
{
    cout <<
    "\nThis program shows how to use cv::Mat and IplImages converting back and forth.\n"
    "It shows reading of images, converting to planes and merging back, color conversion\n"
    "and also iterating through pixels.\n"
    "Call:\n"
    "./image [image-name Default: lena.jpg]\n" << endl;
}

int main(int argc, char *argv[])
{
    help();
    const char* imagename = argc > 1 ? argv[1] : "lena.jpg";
    Mat img = imread(imagename); // the newer cvLoadImage alternative, MATLAB-style function
    if(img.empty())
    {
        fprintf(stderr, "Can not load image %s\n", imagename);
        return -1;
    }
    if( !img.data ) // check if the image has been loaded properly
        return -1;

    Mat img_yuv;
    cvtColor(img, img_yuv, CV_BGR2YCrCb); // convert image to YUV color space. The output image will be created automatically

    vector<Mat> planes; // Vector is template vector class, similar to STL's vector. It can store matrices too.
    split(img_yuv, planes); // split the image into separate color planes

    imshow("image with grain", img);

    waitKey();

    return 0;

}

---

I get the following errors:

Undefined symbols for architecture x86_64:
 "cv::split(cv::Mat const&, std::__1::vector<cv::Mat, std::__1::allocator<cv::Mat> >&)", referenced from:
  _main in main1.o
 "cv::imread(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int)", referenced from:
  _main in main1.o
 "cv::imshow(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, cv::_InputArray const&)", referenced from:
  _main in main1.o
 ld: symbol(s) not found for architecture x86_64
 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Any idea how to resolve this?

Answer 1

I had the same problem. A build setting default seems to be different in Xcode 4.5.

Under "Build Settings"--> Apple LLVM compiler 4.1 - Language >

C++ Standard Library:= Change from libc++ (LLVM ...) to libstdc++ (GNU C++ ...).

Answer 2

It's very likely that OpenCV has not been compiled with C++11 settings, while the program is. Set the build of your tool without C++11 switches (i.e. -std=c++11 -stdlib=libc++).