swift - VNDetectFaceRectanglesRequest 没有调用 completionHandler

Question

我正在尝试检测面部。它无法检测到，因为未调用 handleFaces。我想知道为什么不调用它，如果我想检测人脸，我该如何解决。

faceDetectionRequest = VNDetectFaceRectanglesRequest(completionHandler: self.handleFaces)

func handleFaces(request: VNRequest, error: Error?) {
    DispatchQueue.main.async {
        //perform all the UI updates on the main queue
        guard let results = request.results as? [VNFaceObservation] else { return }
        self.myView.removeMask()
        for face in results {
            self.myView.drawFaceboundingBox(face: face)
        }
    }
}

请帮我解决这个问题。

Answer 1

我认为您应该在将请求作为参数的处理程序上调用 perform 以执行检测。如果您有静态图像，我认为这可以工作：

import UIKit
import Vision

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        let faceDetectionRequest = VNDetectFaceRectanglesRequest(completionHandler: self.handleFaces)
        guard let image = UIImage(named: "sample") else { return }
        guard let cgImage = image.cgImage else { return }
        let handler = VNImageRequestHandler(cgImage: cgImage, options: [:])
        do {
            try handler.perform([faceDetectionRequest])
        } catch let reqErr {
            print("Failed to perform request:", reqErr)
        }
    }

    func handleFaces(request: VNRequest, error: Error?) {
        DispatchQueue.main.async {
            //perform all the UI updates on the main queue
            guard let results = request.results as? [VNFaceObservation] else { return }
            self.myView.removeMask()
            for face in results {
                self.myView.drawFaceboundingBox(face: face)
            }
        }
    }
}

我必须感谢来自 Let's Build That App 的 Brian Voong 的代码：https ://www.letsbuildthatapp.com/course_video?id=1572 。