如何在iPhone上显示进度指示器叠加/ HUD？

import UIKit

func showProgressHUD() {
    let spinnerView = UIActivityIndicatorView(style: .large)
    spinnerView.color = .white
    spinnerView.startAnimating()
    
    let blurEffect = UIBlurEffect(style: .dark)
    let visualEffectView = UIVisualEffectView(effect: blurEffect)
    visualEffectView.frame = view.bounds
    visualEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    visualEffectView.contentView.addSubview(spinnerView)
    spinnerView.center = visualEffectView.contentView.center
    
    view.addSubview(visualEffectView)
}

showProgressHUD()

func hideProgressHUD() {
    for subview in view.subviews where subview is UIVisualEffectView {
        subview.removeFromSuperview()
    }
}