如何在swift中从webView打开外部链接？

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {
    
    var webView: WKWebView!
    
    override func loadView() {
        webView = WKWebView()
        webView.navigationDelegate = self
        view = webView
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let url = URL(string: "https://www.example.com")!
        webView.load(URLRequest(url: url))
        webView.allowsBackForwardNavigationGestures = true
    }
    
    // 处理外部链接的跳转
    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        if navigationAction.targetFrame == nil {
            webView.load(navigationAction.request)
        }
        decisionHandler(.allow)
    }
}