c++ - Adding external libraries deploying QT app mac OSX

Question

I am facing difficulty while deploying QT app which is using openCV as an external library.

In http://doc.qt.io/qt-5/osx-deployment.html page it says : To include a 3rd party library in the application bundle, copy the library into the bundle manually, after the bundle is created. So where should I copy inside the.app folder?

Also http://www.dafscollaborative.org/opencv-deploy.html blog is saying to use install_name_tool to deploy openCV with Qt app, but the path that he is using is not clear to me and its giving error in my case.

So, what should I do to deploy my QT app with opencv library?

Running otool -L MyApplication.app/Contents/MacOS/MyApplication gives me following :

@rpath/libopencv_calib3d.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_features2d.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_highgui.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_videoio.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_imgcodecs.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_video.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_photo.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_ml.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_imgproc.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_flann.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/libopencv_core.3.2.dylib (compatibility version 3.2.0, current version 3.2.0)
@rpath/QtWidgets.framework/Versions/5/QtWidgets (compatibility version 5.10.0, current version 5.10.0)
@rpath/QtGui.framework/Versions/5/QtGui (compatibility version 5.10.0, current version 5.10.0)
@rpath/QtCore.framework/Versions/5/QtCore (compatibility version 5.10.0, current version 5.10.0)
/System/Library/Frameworks/DiskArbitration.framework/Versions/A/DiskArbitration (compatibility version 1.0.0, current version 1.0.0)
/System/Library/Frameworks/IOKit.framework/Versions/A/IOKit (compatibility version 1.0.0, current version 275.0.0)
@rpath/QtXml.framework/Versions/5/QtXml (compatibility version 5.10.0, current version 5.10.0)
/System/Library/Frameworks/OpenGL.framework/Versions/A/OpenGL (compatibility version 1.0.0, current version 1.0.0)
/System/Library/Frameworks/AGL.framework/Versions/A/AGL (compatibility version 1.0.0, current version 1.0.0)
/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 307.5.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1238.50.2)

Answer 1

In macOS, a dylib has an embedded path to where it expects to be placed in the file system. Applications linking against those dylibs will expect to find the dylib in that location. This is the path that you can modify with install_name_tool and inspect with otool -L.

@rpath is a placeholder that represents the runtime path of the application linking against the dll. The runtime path of the application is set by passing the -rpath flag to the linker. The runtime path itself can use the placeholder @executable_path, with which you can set paths relative to the executable.

In your case, if you set -rpath @executable_path/../Frameworks, you must copy the Qt libraries to the Frameworks folder inside the application bundle for your application to find them.