如何根据UIImageView内容更改NSLayout约束常量？

Question

我试图通过将imageview内容位置获取为CGRECT来更改NSLayout约束常量。但是我通过contentRect获得的内容位置是不同的。

这是我用来获取内容位置的扩展名。

extension UIImageView {

      var contentRect: CGRect {
        guard let image = image else { return bounds }
        guard contentMode == .scaleAspectFit else { return bounds }
        guard image.size.width > 0 && image.size.height > 0 else { return bounds }

        let scale: CGFloat
        if image.size.width > image.size.height {
            scale = bounds.width / image.size.width
        } else {
            scale = bounds.height / image.size.height
        }

        let size = CGSize(width: image.size.width * scale, height: image.size.height * scale)
        let x = (bounds.width - size.width) / 2.0
        let y = (bounds.height - size.height) / 2.0

        return CGRect(x: x, y: y, width: size.width, height: size.height)
    }

 override func viewDidLoad(){

        super.viewDidLoad()

        imageVw.image = imagePassed
        imageVw.backgroundColor = colorPassed
        setStyle(toTextField: topText)
        setStyle(toTextField: bottomText)
        let ht = imageVw.contentRect.minY + imageVw.contentSize.height
        topConstraint.constant = self.view.frame.height - ht
        self.view.layoutIfNeeded()

        print("contentRect value  \(imageVw.contentRect)")
        print("point   \(imageVw.contentRect.minY)")
        print("image height  \(imageVw.contentSize)")

    }