如何调整UITextField占位符文本的大小以适合UITextField宽度？

import UIKit

// 创建UITextField对象
let textField = UITextField(frame: CGRect(x: 0, y: 0, width: 200, height: 40))

// 设置UITextField的其他属性
textField.borderStyle = .roundedRect
textField.backgroundColor = .white

// 创建NSAttributedString对象，并设置占位符文本的样式和属性
let placeholderText = "请输入内容"
let attributes: [NSAttributedString.Key: Any] = [
    .font: UIFont.systemFont(ofSize: 14),
    .foregroundColor: UIColor.gray
]
let attributedPlaceholder = NSAttributedString(string: placeholderText, attributes: attributes)

// 调整字体大小以适应UITextField的宽度
let placeholderSize = attributedPlaceholder.size()
let scaleFactor = textField.bounds.width / placeholderSize.width
let adjustedFontSize = UIFont.systemFont(ofSize: 14).pointSize * scaleFactor
let adjustedAttributes: [NSAttributedString.Key: Any] = [
    .font: UIFont.systemFont(ofSize: adjustedFontSize),
    .foregroundColor: UIColor.gray
]
let adjustedAttributedPlaceholder = NSAttributedString(string: placeholderText, attributes: adjustedAttributes)

// 将调整后的NSAttributedString对象赋值给UITextField的attributedPlaceholder属性
textField.attributedPlaceholder = adjustedAttributedPlaceholder