在ARSCNView中获取像素颜色的一种解决方法是使用hitTest(_:options:)方法来获取点击的场景节点，并通过hitTestResult的textureCoordinates属性来获取对应的纹理坐标。然后，可以使用CVPixelBuffer和CVPixelBufferGetBaseAddress函数来获取像素数据，并使用UnsafeMutablePointer读取像素颜色。

下面是一个示例代码：

import ARKit

extension ARSCNView {
    func getPixelColor(at point: CGPoint) -> UIColor? {
        guard let frame = self.session.currentFrame else {
            return nil
        }
        
        let hitTestOptions: [SCNHitTestOption : Any] = [.boundingBoxOnly: true, .firstFoundOnly: true]
        
        let hitTestResults = self.hitTest(point, options: hitTestOptions)
        
        if let hitTestResult = hitTestResults.first {
            let textureCoordinates = hitTestResult.textureCoordinates(withMappingChannel: 0)
            
            let width = frame.capturedImage.width
            let height = frame.capturedImage.height
            
            let x = Int(textureCoordinates.x * CGFloat(width))
            let y = Int(textureCoordinates.y * CGFloat(height))
            
            if let pixelBuffer = frame.capturedImage {
                CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly)
                
                let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer)
                
                let bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)
                let buffer = baseAddress?.assumingMemoryBound(to: UInt8.self)
                
                let pixel = buffer! + y * bytesPerRow + x * 4
                
                let red = CGFloat(pixel[0]) / 255.0
                let green = CGFloat(pixel[1]) / 255.0
                let blue = CGFloat(pixel[2]) / 255.0
                let alpha = CGFloat(pixel[3]) / 255.0
                
                CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly)
                
                return UIColor(red: red, green: green, blue: blue, alpha: alpha)
            }
        }
        
        return nil
    }
}

然后，你可以使用以下方式来调用该方法：

let pixelColor = arscnView.getPixelColor(at: CGPoint(x: 100, y: 100))

上述代码中的CGPoint(x: 100, y: 100)是屏幕上的一个点，表示要获取该点处的像素颜色。你可以根据需要更改该值。