如何在连接到NSTextAttachment类型的textView上居中显示图像？

// 创建一个NSTextAttachment对象，并设置图像
let textAttachment = NSTextAttachment()
textAttachment.image = UIImage(named: "image_name")

// 调整图像的大小和位置，使其居中显示
let textViewWidth = textView.frame.width
let imageWidth = textViewWidth - 20 // 假设图像宽度为textView宽度减去一些边距
let imageHeight = imageWidth * (textAttachment.image!.size.height / textAttachment.image!.size.width) // 根据图像宽度等比例计算高度
textAttachment.bounds = CGRect(x: 0, y: 0, width: imageWidth, height: imageHeight)

// 将NSTextAttachment对象插入到textView的富文本中
let attributedString = NSMutableAttributedString(attributedString: textView.attributedText)
let attachmentString = NSAttributedString(attachment: textAttachment)
attributedString.append(attachmentString)
textView.attributedText = attributedString