Accessing files in resources folder in mac osx app bundle - c++

Question

I would like to access files which are inside Resources in app bundle. Unfortunately i cannot use QT resorces, as i'm using CascadeClassifier from opencv. My current paths are
const std::string FACE_CLASIFIER_PATH = "/Resources/haarcascade_frontalface_default.xml";
const std::string EYES_CLASIFIER_PATH = "/Resources/haarcascade_mcs_eyepair_big.xml";
I also tried
const std::string FACE_CLASIFIER_PATH = "../Resources/haarcascade_frontalface_default.xml";
const std::string EYES_CLASIFIER_PATH = "../Resources/haarcascade_mcs_eyepair_big.xml";
But nether of them work. As for config both files are present inside MyApp.app/Contents/Resources, i include them using qmake
mac {
APP_XML_FILES.files = ../haarcascade_frontalface_default.xml ../haarcascade_mcs_eyepair_big.xml
APP_XML_FILES.path = Contents/Resources
QMAKE_BUNDLE_DATA += APP_XML_FILES
}
I would appreciate any help with this issue

Answer 1

You don't say what you want to do with the files, though that could be due to my lack of knowledge of opencv. However you can use the Core Foundation classes to get paths to files in the resources folder: -
CFURLRef appUrlRef;
appUrlRef = CFBundleCopyResourceURL(CFBundleGetMainBundle(), CFSTR("somefile"), NULL, NULL);
// do something with the file
//...
// Ensure you release the reference
CFRelease(appUrlRef);
With a CFURLRef, you can use Apple's documentation to get what you need from it.
For example, if you want a file path: -
CFStringRef filePathRef = CFURLCopyPath(appUrlRef);
// Always release items retrieved with a function that has "create or "copy" in its name
CFRelease(filePathRef);
From the file path, we can get a char* to the path: -
const char* filePath = CFStringGetCStringPtr(filePathRef, kCFStringEncodingUTF8);
So, putting it all together, if you want to get a char* path to haarcascade_mcs_eyepair_big.xml: -
CFURLRef appUrlRef = CFBundleCopyResourceURL(CFBundleGetMainBundle(), CFSTR("haarcascade_mcs_eyepair_big.xml"), NULL, NULL);
CFStringRef filePathRef = CFURLCopyPath(appUrlRef);
const char* filePath = CFStringGetCStringPtr(filePathRef, kCFStringEncodingUTF8);
// Release references
CFRelease(filePathRef);
CFRelease(appUrlRef);