Passing CGPoint array back to swift

Question

does anyone know if it is possible to pass an array of CGPoint from objective c++ to swift?

I am able to pass CGPoint back to swift. However, I was not able to figure out how to pass the value back as an array.

Here is the code I used to pass it back to swift.

OpenCVWrapper.mm

+(CGPoint) detectCircle:(UIImage *)image
{
CGPoint pointArray;

cv::Mat img;
UIImageToMat(image, img);

cv::Mat grayMat;
cvtColor(img, grayMat, CV_BGR2GRAY);

cv::Mat dilateMat;
cv::Mat kernel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(7,7));
cv::morphologyEx(grayMat, dilateMat, cv::MORPH_OPEN, kernel);

cv::Mat cannyMat;
Canny(dilateMat, cannyMat, 10, 100);

cv::Mat guassianMat;

cv::GaussianBlur(cannyMat, guassianMat, cv::Size(11,13), 0);

std::vector<cv::Vec3f> circleMat;
cv::HoughCircles(guassianMat, circleMat, CV_HOUGH_GRADIENT, 1, cannyMat.rows / 15,120, 10, 0, 30);

cv::Mat houghCircles;
houghCircles.create(guassianMat.rows, guassianMat.cols, CV_8UC1);

for( size_t i = 0; i < circleMat.size(); i++ )
{
    cv::Vec3i parameters = circleMat[i];
    double x, y;
    int r;

    x = parameters[0];
    y = parameters[1];
    r = int(parameters[2]);

    pointArray.x = x;
    pointArray.y = y;

}


return pointArray;
}

OpenCVWrapper.h

+(CGPoint) detectCircle: (UIImage *)image;

viewController.Swift

@IBAction func detectBtn(_ sender: Any) {
    var points : CGPoint = OpenCVWrapper.detectCircle(adjustBtightnessImage)
    print(points)

}

Answer 1

The best way to do this is to use NSValue to wrap it as @OOPer said.

The main reason is that CGPoint is not an object type in Objective-C. You can't put it directly in an NSArray . You need to wrap it in NSValue .

// Objective-C
+ (NSArray<NSValue *> *)detectCircle:(UIImage *)image {
  return @[
           [NSValue valueWithCGPoint:CGPointMake(10, 10)],
           [NSValue valueWithCGPoint:CGPointMake(10, 20)]
           ];
}

// swift
let points = Circle.detect(UIImage()).map { $0.cgPointValue }