iOS Swift:如何正确缩小图像的比例？

let scaledImage = originalImage.scale(to: CGSize(width: originalImage.size.width/2, height: originalImage.size.height/2))

func scaleImage(image: UIImage, scale: CGFloat) -> UIImage? {
    let size = CGSize(width: image.size.width * scale, height: image.size.height * scale)
    UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
    image.draw(in: CGRect(origin: .zero, size: size))
    let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return scaledImage
}

let scaledImage = scaleImage(image: originalImage, scale: 0.5)