Use OpenCV in Xcode 4 for an Object Oriented Mac OS X Application

First of all you have to install OpenCV in Mac OS X. Then in Xcode create a new Mac OS X Application project of type “Command Line Tool”.

Set a “Product Name” and choose “Foundation” for “Type” option.

In the “Build Settings” tab (clicking on the projects blue icon on the left) add following values for those options:

Inside “Search Paths”:
Header Search Paths: /usr/local/include
Library Search Paths: /usr/local/lib
Inside “Linking”:
Other Linker Flags: -lopencv_core -lopencv_highgui -lopencv_imgproc

NOTE: You can add more libraries in “Other Linker Flags” to add more OpenCV functionality, for example:

-lopencv_core -lopencv_highgui -lopencv_imgproc -lopencv_legacy -lopencv_contrib -lopencv_calib3d -lopencv_features2d -lopencv_flann -lopencv_ml -lopencv_objdetect -lopencv_video

If you want to also use the C functions available in OpenCV change inside “Build Options” the next parameter:

Compiler for C/C++/Objetive-C: LLVM GCC 4.2

Change the extension of “main.m” file to “main.mm“. This makes the code to be interpreted as Objetive-C++ and not only as Objetive-C.

Now (VERY IMPORTANT) inside the .pch file of the “Supporting Files” folder add BEFORE any other import the following code:

#ifdef __cplusplus
    #import "opencv2/opencv.hpp"
#endif

This is because OpenCV has a MIN macro defined that also exists in Apple framework, and if you don’t have the one in OpenCV you may have errors like “LLVM GCC 4.2 Error: Statement-expressions are allowed only inside functions” or “opencv2/core/core.hpp:433: error: statement-expressions are allowed only inside functions“. The import in surrounded by that “ifdef” so the files that don’t use Objetive-C++ code can maintain the “.m” extension and not be forced to change all them to “.mm“.

Fill “main.mm” with this example code, that is in fact the Object Oriented version code of the previous example in Use OpenCV on Xcode 4 for a Mac OS X Application:

//
// main.mm
// OpenCVOOTest
//
// Created by __MyName__ on 16/09/11.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "opencv2/opencv.hpp"

using namespace cv;

int main (int argc, const char * argv[])
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    
    Mat img(cv::Size(640, 480), CV_8UC3);
    
    circle(img, cv::Point(320, 240), 100, Scalar(255, 0, 0, 255), 5, 8, 0);
    
    namedWindow("OpenCV Window", CV_WINDOW_NORMAL);

    imshow("OpenCV Window", img);
    
    waitKey(0);
    
    [pool drain];
    return 0;
}

If you have this error while linking:

"Undefined symbols for architecture x86_64:"

Followed by multiple function names, you have to change the programs architecture to i386. Inside “Build Settings” of the project change the option “Arquitectures” to “32-bit Intel”. This by itself may not solve the problem, as OpenCV must be also compiled for a i386 32 bits architecture.

Sources: http://stackoverflow.com/questions/3810800/how-to-include-opencv-in-cocoa-application
http://computer-vision-talks.com/2011/03/opencv-build-script-with-xcode-4-support-is-here

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  1. Thanks a lot, you saved my day. There seeems to be a lot of ‘How To’s around, but none of them worked for my system (opencv 2.4.2 with macports, XCode 4.5 on 10.7.4) I did not need to edit the .pch file (didnt’ find it anyway).
    Cheers

  2. I follow these steps but when I compile I obtained these errors:

    /opt/local/include/opencv2/core/types_c.h
    /opt/local/include/opencv2/core/types_c.h:742: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/types_c.h:774: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/types_c.h:791: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/types_c.h:807: Implicit conversion shortens 64-bit value into a 32-bit value
    /opt/local/include/opencv2/core/core_c.h
    /opt/local/include/opencv2/core/core_c.h:1118: ‘assert’ was not declared in this scope
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:66: ‘::clock_t’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:68: ‘::tm’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:70: ‘::clock’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:71: ‘::difftime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:72: ‘::mktime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:73: ‘::time’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:74: ‘::asctime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:75: ‘::ctime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:76: ‘::gmtime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:77: ‘::localtime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/ctime:78: ‘::strftime’ has not been declared
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1839: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1846: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1854: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1861: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1873: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1880: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1883: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1895: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1900: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1908: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1912: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1932: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1968: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:1976: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:2210: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:2259: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/locale_facets.tcc:2288: Invalid use of incomplete type ‘struct tm’
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/wchar.h
    /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/wchar.h:155: Forward declaration of ‘struct tm’
    /opt/local/include/opencv2/core/operations.hpp
    /opt/local/include/opencv2/core/operations.hpp:3446: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/core/operations.hpp:3446: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated)
    /opt/local/include/opencv2/core/operations.hpp:223: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/operations.hpp:216: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/operations.hpp:230: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/mat.hpp
    /opt/local/include/opencv2/core/mat.hpp:772: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/core/mat.hpp:781: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/core/mat.hpp:792: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/legacy/legacy.hpp
    /opt/local/include/opencv2/legacy/legacy.hpp:1464: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/legacy/legacy.hpp:1478: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/flann/nn_index.h
    /opt/local/include/opencv2/flann/nn_index.h:75: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/nn_index.h:76: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/allocator.h
    /opt/local/include/opencv2/flann/allocator.h:131: Implicit conversion shortens 64-bit value into a 32-bit value
    /opt/local/include/opencv2/flann/allocator.h:142: Implicit conversion shortens 64-bit value into a 32-bit value
    /opt/local/include/opencv2/flann/allocator.h:158: Implicit conversion shortens 64-bit value into a 32-bit value
    /opt/local/include/opencv2/flann/kdtree_single_index.h
    /opt/local/include/opencv2/flann/kdtree_single_index.h:217: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/kdtree_single_index.h:218: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/kmeans_index.h
    /opt/local/include/opencv2/flann/kmeans_index.h:154: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/kmeans_index.h:209: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/hierarchical_clustering_index.h
    /opt/local/include/opencv2/flann/hierarchical_clustering_index.h:155: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/hierarchical_clustering_index.h:210: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/lsh_table.h
    /opt/local/include/opencv2/flann/lsh_table.h:159: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/lsh_table.h:240: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/lsh_index.h
    /opt/local/include/opencv2/flann/lsh_index.h:195: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/lsh_index.h:196: There are no arguments to ‘assert’ that depend on a template parameter, so a declaration of ‘assert’ must be available
    /opt/local/include/opencv2/flann/timer.h
    /opt/local/include/opencv2/flann/timer.h:47: ‘clock_t’ does not name a type
    /opt/local/include/opencv2/flann/timer.h:69: ‘startTime’ was not declared in this scope
    /opt/local/include/opencv2/flann/timer.h:69: ‘clock’ was not declared in this scope
    /opt/local/include/opencv2/flann/timer.h:77: ‘clock_t’ was not declared in this scope
    /opt/local/include/opencv2/flann/timer.h:77: Expected `;’ before ‘stopTime’
    /opt/local/include/opencv2/flann/timer.h:78: ‘stopTime’ was not declared in this scope
    /opt/local/include/opencv2/flann/timer.h:78: ‘startTime’ was not declared in this scope
    /opt/local/include/opencv2/flann/timer.h:78: ‘CLOCKS_PER_SEC’ was not declared in this scope
    /opt/local/include/opencv2/core/internal.hpp
    /opt/local/include/opencv2/core/internal.hpp:437: ‘assert’ was not declared in this scope
    /opt/local/include/opencv2/core/internal.hpp:443: ‘assert’ was not declared in this scope
    (null): -Wuninitialized is not supported without -O

    please help me. I lost a lot of time

    • I see that you have OpenCV installed in “/opt/local”, have you supplied the correct paths in the configuration values? In the post I say to use “/usr/local/include” for “Header Search Paths” but if you have your include files in “/opt/local/include” you have to configure with that path. The same for “Library Search Paths”.

      It looks like you installed OpenCV with MacPorts, am I righ?

      • yes , I installed opencv with macports and I changed all configurations.
        as :
        Header Search Paths: /opt/local/include
        Library Search Paths: /opt/local/lib

        and I added many libraries to my file using : File-> Add Files.

        an this is my code main.cpp

        //
        // main.cpp
        // MOG
        //
        // Created by Rafik Gouiaa on 2013-02-07.
        // Copyright (c) 2013 Rafik Gouiaa. All rights reserved.
        //

        #include
        #include
        #include
        #include
        #include
        #include “opencv2/features2d/features2d.hpp”
        #include”opencv2/highgui/highgui.hpp”
        #include”opencv2/core/core.hpp”
        #include”opencv2/legacy/legacy.hpp” (BruteForceMatcher is defined here!)
        int main(int argc, char** argv)
        {
        IplImage * pInpImg = 0;

        // Load an image from file – change this based on your image name
        pInpImg = cvLoadImage(“my_image.jpg”, CV_LOAD_IMAGE_UNCHANGED);
        if(!pInpImg)
        {
        fprintf(stderr, “failed to load input image\n”);
        return -1;
        }

        // Write the image to a file with a different name,
        // using a different image format — .png instead of .jpg
        if( !cvSaveImage(“my_image_copy.png”, pInpImg) )
        {
        fprintf(stderr, “failed to write image file\n”);
        }

        // Remember to free image memory after using it!
        cvReleaseImage(&pInpImg);

        return 0;
        }

  3. Say Hong TAN

    Hi, Xcode throws up error when using Xcode 5 – NSAutoreleasepool not used in ARC.

    You may wish to update your post to comment out

    //NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    and
    //[pool drain];

    I’m running Mavericks, Xcode 5 and Opencv 2.4.8

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