PIP相机效果iOS Swift

Question

如何在iOS Swift应用程序中实现PIP效果。我尝试了但是在放置和移动内部图片的情况下结果不准确。 这是我的尝试：

    @IBOutlet var galleryImageView: UIImageView!
    @IBOutlet var background: UIImageView!
    @IBOutlet var behindView: UIView!
    override func viewDidLoad() {
        super.viewDidLoad()
        let image = UIImage(named: "ph3")
        let maskingImage = UIImage(named: "mask")
        galleryImageView.image = maskImage(image: image!, mask: maskingImage!)
        galleryImageView.contentMode = .scaleAspectFill
        background.image = UIImage(named: "ph3")?.stackBlur(10)
        let maskingLayer = CALayer()
        maskingLayer.frame = behindView.bounds
        maskingLayer.contents = (galleryImageView.image?.cgImage! as Any)
        behindView.layer.mask = maskingLayer
        let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(self.panGestureDetected))
        panGestureRecognizer.delegate = self
        self.galleryImageView.addGestureRecognizer(panGestureRecognizer)
    }
    func maskImage(image:UIImage, mask:(UIImage))->UIImage{
        let imageReference = image.cgImage
        let maskReference = mask.cgImage
        let imageMask = CGImage(maskWidth: maskReference!.width,
                                height: maskReference!.height,
                                bitsPerComponent: maskReference!.bitsPerComponent,
                                bitsPerPixel: maskReference!.bitsPerPixel,
                                bytesPerRow: maskReference!.bytesPerRow,
                                provider: maskReference!.dataProvider!, decode: nil, shouldInterpolate: true)
        let maskedReference = imageReference!.masking(imageMask!)
        let maskedImage = UIImage(cgImage:maskedReference!)
        return maskedImage
    }

galleryImageView是内部imageView

结果应该是：