使用swift在WKWebView中呈现数据之前显示自定义加载器

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {
    var webView: WKWebView!
    var loadingView: UIView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建自定义加载器视图
        loadingView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        loadingView.center = view.center
        loadingView.backgroundColor = UIColor.lightGray
        loadingView.layer.cornerRadius = 10
        
        let activityIndicator = UIActivityIndicatorView(style: .whiteLarge)
        activityIndicator.center = CGPoint(x: loadingView.bounds.width / 2, y: loadingView.bounds.height / 2)
        activityIndicator.startAnimating()
        loadingView.addSubview(activityIndicator)
        
        // 创建WKWebView并设置代理
        webView = WKWebView(frame: view.bounds)
        webView.navigationDelegate = self
        
        // 将WKWebView添加到视图层级中
        view.addSubview(webView)
        
        // 加载网页
        let url = URL(string: "https://www.example.com")
        let request = URLRequest(url: url!)
        webView.load(request)
    }
    
    // WKNavigationDelegate方法：开始加载网页
    func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        // 显示自定义加载器视图
        view.addSubview(loadingView)
    }
    
    // WKNavigationDelegate方法：网页加载完成
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        // 隐藏自定义加载器视图
        loadingView.removeFromSuperview()
    }
    
    // WKNavigationDelegate方法：网页加载失败
    func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
        // 隐藏自定义加载器视图
        loadingView.removeFromSuperview()
        
        // 处理加载失败的情况
    }
}