Weird crash when I try to attribute a variable in OpenCV IOS - c++

Question

There is something I'm not able to understand. I'm using OpenCV IOS for my IOS Device.
I have a C++ class with a private variable cv::Rect . This variable is located to my .h file.
In my .cpp file, I have a method which creates a cv::Rect. Then, I would like to attribute this new created cv::Rect to my class variable but It crashs and I do not understand why.
.h file
class detection {
public:
detection();
cv::Mat processImage(cv::Mat frame);
cv::Mat detectFace(cv::Mat frame);
public:
cv::Rect getRectangleDetection();
void setRectangleDetection(cv::Rect& rect);
private:
cv::Rect _rectangeDetect;
};
.cpp file
cv::Mat detection::processImage(cv::Mat frame){
Mat originalColorImage;
frame.copyTo(originalColorImage);
int cx = frame.cols/2;
int cy = frame.rows/2;
int width = 1000;
int height = 1000;
NSLog(#"[INFO] Rectangle creation");
cv::Rect rect1(cx-width/2, cy-height/2, width,height);
cv::Rect test2;
//test2 = rect1;//It works !
setRectangleDetection(rect1); // or _rectangeDetect = rect1 --> both don't work
cv::rectangle( originalColorImage,rect1,
cv::Scalar(255, 0, 0),4);
return originalColorImage;
}
I took a look at the crash report and I saw that :
exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000000
Triggered by Thread: 0
Filtered syslog:
None found
Thread 0 name: Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0 detect 0x000000010007f580 cv::Rect_<int>::operator=(cv::Rect_<int> const&) (types.hpp:1689)
1 detect 0x000000010007f504 OpenCV::setRectangleDetection(cv::Rect_<int>) (OpenCV.mm:172) //This is the setter but If I'm not using the setter the error will come from _rectangleDetect = rect1.
I tried also to initialize the variable cv::Rect but same behavior.
Do you have any idea what's happen ? Really, I tried to figure out why but without success.
I used a lot OpenCv before and It's the first time something like that happens.
Thank !

Answer 1

Okey I found the problem. It was a silly one.
Actually, on my other class when I was using the detection class, I forgot to initialize the object.
Detection _detect = new Detection()
As I did not get any error from the following line and by the fact that the behavior seemed to be good (even with some debug), I did not think of that.
_detect->processImage(frame);
Thank you guys anyway.