获取UIScrollView视图图片，解决遮挡部分无法加进图片问

前段时间有个需求：将滚动视图中的所有内容保存为图片。
写了一种通用的，检查contentSize没有问题之后运行保存，问题来了，无法将被遮住的部分也划分进图片区域，图片只有可见区域，反复检查区域宽高应该是没有问题的，iOS12可以全部保存为图片，iOS13以上的就不行。
百度UIScrollView生成图片，基本都和我写的一样，最后搜遮挡才搜到一个解决方案，废话不多说，上新鲜代码

extension UIScrollView {
    func getImageOfScrollView() -> UIImage {
        var image = UIImage()
        
        UIGraphicsBeginImageContextWithOptions(self.contentSize, false, UIScreen.main.scale)
        
        // save initial values
        let savedContentOffset = self.contentOffset
        let savedFrame = self.frame
        let savedBackgroundColor = self.backgroundColor    // reset offset to top left point
        self.contentOffset = .zero
        // set frame to content size
        self.frame = CGRect(x: 0, y: 0, width: self.contentSize.width, height: self.contentSize.height)
        // remove background
        self.backgroundColor = UIColor.clear
        
        // make temp view with scroll view content size
        // a workaround for issue when image on ipad was drawn incorrectly
        let tempView = UIView(frame: CGRect(x:0, y:0, width: self.contentSize.width, height:self.contentSize.height))
        
        // save superview
        let tempSuperView = self.superview    // remove scrollView from old superview
        self.removeFromSuperview()
        // and add to tempView
        tempView.addSubview(self)
        
        // render view
        // drawViewHierarchyInRect not working correctly
        tempView.layer.render(in: UIGraphicsGetCurrentContext()!)
        // and get image
        image = UIGraphicsGetImageFromCurrentImageContext()!
        
        // and return everything back
        tempView.subviews[0].removeFromSuperview()
        tempSuperView?.addSubview(self)
        
        // restore saved settings
        self.contentOffset = savedContentOffset
        self.frame = savedFrame
        self.backgroundColor = savedBackgroundColor
        UIGraphicsEndImageContext()
        
        return image
    }
}

我原本写的如下

extension UIScrollView {
    var screenshotImage: UIImage? {
        var image: UIImage? = nil
        UIGraphicsBeginImageContext(contentSize)
        
        let formerContentOffset = contentOffset
        let formerFrame = frame
        self.contentOffset = .zero
        self.frame = CGRect(origin: CGPoint.zero, size: contentSize)
        
        UIGraphicsBeginImageContextWithOptions(contentSize, false, UIScreen.main.scale)
        if let currentContext = UIGraphicsGetCurrentContext() {
            self.layer.render(in: currentContext)
            image = UIGraphicsGetImageFromCurrentImageContext()
        }
        UIGraphicsEndImageContext()
        
        self.contentOffset = formerContentOffset
        self.frame = formerFrame
        
        return image
    }
}

我有单独项目测试过原本写的版本，是没有问题的，也没找到具体原因，如有找到的请点评。