当需要截取 TableView 或 ScrollView 中的全部内容时，可以采用以下方法：

/// 长截屏
func fullScreenShot(_ scrollView: UIScrollView) -> UIImage {
        // 记录当前 scrollView 的"偏移量"和"坐标"
        let savedContentOffset = scrollView.contentOffset
        let savedScrollViewFrame = scrollView.frame
        
        scrollView.contentOffset = .zero
        scrollView.frame = CGRect(origin: .zero, size: scrollView.contentSize)
        
        UIGraphicsBeginImageContextWithOptions(scrollView.contentSize, true, UIScreen.main.scale)
        scrollView.layer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()!
        
        // 重置
        scrollView.contentOffset = savedContentOffset
        scrollView.frame = savedScrollViewFrame
        
        UIGraphicsEndImageContext()
        
        return image
}