ios - 在显示之前加载 ViewController WebView

Question

我有一个带有包含 WebView 的 ViewController 的应用程序。因为 WebView 显示的网站非常大，所以我想在应用程序启动时加载 ViewController，这样一旦用户使用 WebView 打开 ViewController，它就会显示已经加载的页面。

我已经尝试覆盖 viewDidLoad()、loadView()、便利的 init() 等，但我放在那里的任何东西似乎都没有在实际显示 ViewController 之前执行。

 let storyboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
 webViewVC = storyboard.instantiateViewController(withIdentifier: "WebViewController")

 if let c = webViewVC.childViewControllers[0] as? WebViewController {

     c.dDelegate = self

     webViewVC.modalPresentationStyle = .popover
     let popover = webViewVC.popoverPresentationController!
     popover.delegate = self
     popover.permittedArrowDirections = .up
     webViewVC.loadView()
     present(webViewVC, animated: true, completion: nil) //if I don't add this line, the ViewController doesn't seem to get created before showing
 }

那么我可以在 present() 之前调用什么来执行 ViewController 的一些代码？我需要加载如下内容:

let wwConfiguration = WKWebViewConfiguration()

webView = WKWebView(frame: CGRect(x: 0, y: 0, width: self.view.layer.frame.width, height: self.view.layer.frame.height), configuration: wwConfiguration)
webView.navigationDelegate = self
webView.uiDelegate = self
let url = URL(string: . . .

Answer 1

您的问题并不完全清楚，但我假设您正在从另一个 View Controller 中展示您的 Web View Controller ，比方说，按下按钮。像这样的……

你需要做的是异步处理这个。

• 实例化您的 WebView Controller
• 开始加载其 WebView
• 等待完成
• 展示 WebView Controller

例子……

WebView Controller

class WebViewController: UIViewController {

    @IBOutlet private weak var webView: WKWebView!

    var didLoadWebView: (() -> Void)!

    func loadWebView(completion: @escaping () -> Void) {
        loadViewIfNeeded()
        didLoadWebView = completion // Save this closure to be called when loaded
        webView.navigationDelegate = self
        webView.load(URLRequest(url: URL(string: "http://apple.com")!))
    }
}

extension WebViewController: WKNavigationDelegate {
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        didLoadWebView() // Call back to the presenting view controller
    }
}

呈现 ViewController

class ViewController: UIViewController {

    @IBAction func showWebView(_ sender: UIButton) {

        let wvc = storyboard!.instantiateViewController(withIdentifier: "WebViewController") as! WebViewController
        wvc.modalPresentationStyle = .popover
        wvc.popoverPresentationController?.sourceView = sender
        wvc.popoverPresentationController?.sourceRect = sender.bounds
        wvc.loadWebView {
            self.present(wvc, animated: true, completion: nil)
        }
    }
}