WKWebView 实现登录认证(包含用户名密码输入框)

WKWebView加载需要登录密码的网页时，默认不实现弹出登录输入框

解决方法：设置代理，实现自定义认证

webView.navigationDelegate = self
...
// MARK: - WKNavigationDelegate
func webView(_ webView: WKWebView, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
    let authenticationMethod = challenge.protectionSpace.authenticationMethod
    switch authenticationMethod {
    case NSURLAuthenticationMethodDefault, NSURLAuthenticationMethodHTTPBasic, NSURLAuthenticationMethodHTTPDigest:
        let alertController = UIAlertController(title: "登录", message: "message", preferredStyle: .alert)
        alertController.addTextField { (textField) in
            textField.placeholder = "UserName"
            textField.textContentType = .username
            textField.returnKeyType = .next
        }
        alertController.addTextField { (textField) in
            textField.placeholder = "Password"
            textField.textContentType = .password
            textField.isSecureTextEntry = true
            textField.returnKeyType = .go
        }
        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (_) in
            completionHandler(.cancelAuthenticationChallenge, nil)
        }
        let loginAction = UIAlertAction(title: "Login", style: .default) { (_) in
            guard let username = alertController.textFields?.first?.text,
                let password = alertController.textFields?.last?.text else {
                return
            }
            let credential = URLCredential(user: username, password: password, persistence: .forSession)
            completionHandler(.useCredential, credential)
        }
        alertController.addAction(cancelAction)
        alertController.addAction(loginAction)
        self.present(alertController, animated: true, completion: nil)
    case NSURLAuthenticationMethodServerTrust:
        completionHandler(.performDefaultHandling, nil)
    default:
        completionHandler(.cancelAuthenticationChallenge, nil)
    }
}