Swift 按变换zoom 在UIView中不起作用

在下面的程序中，无论我在CGAffineTransform(scaleX:Y:)的参数中输入什么值，我都会得到相同的绘制结果.

为什么会这样呢？

import UIKit

class ViewController: UIViewController {
  
  override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    self.view.backgroundColor = .gray
  }

  override func viewWillAppear(_ animated: Bool) {
    let scalingView = ScalingView(frame: self.view.bounds)
    self.view.addSubview(scalingView)
  }
}

import UIKit

class ScalingView: UIView {
  let subview: UIView!
  
  override init(frame: CGRect) {
    subview = UIView()
    super.init(frame: frame)
    addSubview(subview)
  }
  
  required init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
  
  override func layoutSubviews() {
    subview.backgroundColor = .white
    let subviewSize = 100
    subview.frame.size = CGSize(width: subviewSize, height: subviewSize)
    subview.center = CGPoint(x: self.bounds.midX, y: self.bounds.midY)
    subview.transform = CGAffineTransform(scaleX: 1, y: 1)
  }
}

subview.transform = CGAffineTransform(scaleX: 1, y: 1)

scaleX: 1, y: 1

subview.transform = CGAffineTransform(scaleX: 2, y: 2)

scaleX: 2, y: 2

subview.transform = CGAffineTransform(scaleX: 0.5, y: 0.5)

scaleX: 0.5, y: 0.5个

https://github.com/ll3Ynxnj/Sample-Swift-ViewScaling.git个