如何从Swift 3 xcode8中UIWebView的url中获取查询字符串参数？

class ViewController: UIViewController, UIWebViewDelegate {
    // ...
    override func viewDidLoad() {
        super.viewDidLoad()
        webView.delegate = self
    }
    // ...
}

func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebView.NavigationType) -> Bool {
    if let url = request.url, let queryItems = URLComponents(url: url, resolvingAgainstBaseURL: false)?.queryItems {
        for item in queryItems {
            let name = item.name
            let value = item.value
            // 在这里处理查询字符串参数
            print("参数名：\(name)，参数值：\(value)")
        }
    }
    return true
}