看完代码后，你声明了一个名为UIViewController的新类，也许你指的是扩展而不是类。
这就是编译器找不到该方法的原因，因为您通过将其命名为UIViewController来创建新类，从而覆盖了该方法。
您需要将class UIViewController {替换为extension UIViewController {

这是我的完整代码：

import UIKit
import Vision

class ViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!
    var imageOrientation = CGImagePropertyOrientation(.up)
    
    override func viewDidAppear(_ animated: Bool) {
        
        super.viewDidAppear(animated)
        
        if let image = UIImage(named: "group") {
            imageView.image = image
            imageView.contentMode = .scaleAspectFit
            imageOrientation = CGImagePropertyOrientation(image.imageOrientation)
            
            guard let cgImage = image.cgImage else {return}
            setupVision(image: cgImage)
        }
    }
    
    private func setupVision (image: CGImage) {
        let faceDetectionRequest = VNDetectFaceRectanglesRequest(completionHandler: self.handelFaceDetectionRequest)
        
        let imageRequestHandler = VNImageRequestHandler(cgImage: image, orientation: imageOrientation, options: [:])
    
        do {
            try imageRequestHandler.perform([faceDetectionRequest])
        }catch let error as NSError {
            print(error)
            return
        }
    }
    
    private func handelFaceDetectionRequest (request: VNRequest?, error: Error?) {
        if let requestError = error as NSError? {
            print(requestError)
            return
        }
        
        guard let image = imageView.image else {return}
        guard let cgImage = image.cgImage else {return}
        
        let imageRect = self.determineScale(cgImage: cgImage, imageViewFrame: imageView.frame)
        
        self.imageView.layer.sublayers = nil
        
        if let results = request?.results as? [VNFaceObservation] {
            for observation in results {
                let faceRect = convertUnitToPoint(originalImageRect: imageRect, targetRect: observation.boundingBox)
                
                let emojiRect = CGRect(x: faceRect.origin.x, y: faceRect.origin.y - 5, width: faceRect.size.width  + 5, height: faceRect.size.height + 5)
            
                let textLayer = CATextLayer()
                textLayer.string = "🦸‍♂️"
                textLayer.fontSize = faceRect.width
                textLayer.frame = emojiRect
                textLayer.contentsScale = UIScreen.main.scale
                
                self.imageView.layer.addSublayer(textLayer)
                
            }
        }
    }

    
}

以及：

import UIKit

class UIViewController {
    
    public func convertUnitToPoint (originalImageRect: CGRect, targetRect: CGRect) -> CGRect {
        
        var pointRect = targetRect
        
        pointRect.origin.x = originalImageRect.origin.x + (targetRect.origin.x * originalImageRect.size.width)
        pointRect.origin.y = originalImageRect.origin.y + (1 - targetRect.origin.y - targetRect.height)
        pointRect.size.width *= originalImageRect.size.width
        pointRect.size.height *= originalImageRect.size.height
        
        return pointRect
    }
    
    public func determineScale (cgImage: CGImage, imageViewFrame: CGRect) -> CGRect {
        let originalWidth = CGFloat(cgImage.width)
        let originalHeigth = CGFloat(cgImage.height)
        
        let imageFrame = imageViewFrame
        let widthRatio = originalWidth / imageFrame.width
        let heigthRatio = originalHeigth / imageFrame.height
        
        let scaleRatio = max(widthRatio, heigthRatio)
        
        let scaledImageWidth = originalWidth / scaleRatio
        let scaledImageHeigth = originalHeigth / scaleRatio
        
        let scaledImageX = (imageFrame.width - scaledImageWidth) / 2
        let scaledImageY = (imageFrame.height - scaledImageHeigth) / 2
        
        return CGRect(x: scaledImageX, y: scaledImageY, width: scaledImageWidth, height: scaledImageHeigth)
    }
    
}

extension CGImagePropertyOrientation {
    
    init(_ orientation: UIImage.Orientation) {
        
        switch orientation {
        case .up: self = .up
        case .upMirrored: self = .upMirrored
        case .down: self = .down
        case .downMirrored: self = .downMirrored
        case .right: self = .right
        case .rightMirrored: self = .rightMirrored
        default: self = .up
        }
    }
}

剪切的第一个代码来自ViewController文件