使用swift在WKWebView上显示活动指示器

Question

我正在处理以下代码，并尝试在页面加载时在视图中显示活动指示器。

我试图实现WKNavigationDelegate方法，但我失败了，因为没有显示。

对于如何解决这个问题，有任何的建议吗？

我没有在任何地方设置SupportWebView视图委托，但我不知道如何在swift中执行它。

import UIKit
import WebKit

class SupportWebView: UIViewController, WKNavigationDelegate {
    @IBOutlet var containerView : UIView? = nil

    var webView: WKWebView?

    override func loadView() {
        super.loadView()
        self.webView = WKWebView()
        self.view = self.webView
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        var dataManager = DataManager.sharedDataManager()
        var url = dataManager.myValidURL
        var req = NSURLRequest(URL:url!)
        self.webView!.loadRequest(req)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func webView(webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        UIApplication.sharedApplication().networkActivityIndicatorVisible = true
    }


    func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
        UIApplication.sharedApplication().networkActivityIndicatorVisible = false
    }
}

Answer 1

如评论所述，您忘记设置webView代表：

override func loadView() {
    super.loadView()
    self.webView = WKWebView()
    self.webView.navigationDelegate = self
    self.view = self.webView
}

Answer 2

您应该将委托方法用于所有其他目的，但是密钥路径监视可以正常用于此目的。

这是一个工作正常的Swift 4实现。

// Somewhere in your view controller
private var loadingObservation: NSKeyValueObservation?

private lazy var loadingIndicator: UIActivityIndicatorView = {
    let spinner = UIActivityIndicatorView()
    spinner.translatesAutoresizingMaskIntoConstraints = false
    spinner.color = .black
    return spinner
}()

override func viewDidLoad() {
    super.viewDidLoad()

    // Setup...

    loadingObservation = webView.observe(\.isLoading, options: [.new, .old]) { [weak self] (_, change) in
        guard let strongSelf = self else { return }

        // this is fine
        let new = change.newValue!
        let old = change.oldValue!

        if new && !old {
            strongSelf.view.addSubview(strongSelf.loadingIndicator)
            strongSelf.loadingIndicator.startAnimating()
            NSLayoutConstraint.activate([strongSelf.loadingIndicator.centerXAnchor.constraint(equalTo: strongSelf.view.centerXAnchor),
                                         strongSelf.loadingIndicator.centerYAnchor.constraint(equalTo: strongSelf.view.centerYAnchor)])
            strongSelf.view.bringSubview(toFront: strongSelf.loadingIndicator)
        }
        else if !new && old {
            strongSelf.loadingIndicator.stopAnimating()
            strongSelf.loadingIndicator.removeFromSuperview()
        }
    }
}

Answer 3

请在下面的代码中工作正常[Swift 4.2]。

@IBOutlet weak var wv: WKWebView!
@IBOutlet weak var activityIndicator: UIActivityIndicatorView!

override func viewDidLoad() {
    super.viewDidLoad()
     loadYoutube(videoID: "KqNS7uAvOxk")     
}

现在加载Youtube视频

 func loadYoutube(videoID:String) {
    guard let youtubeURL = URL(string: "https://www.youtube.com/embed/\(videoID)")
        else { return }
    wv.load( URLRequest(url: youtubeURL) )
    wv.navigationDelegate = self
}

在此功能下实现：

 func showActivityIndicator(show: Bool) {
    if show {
        activityIndicator.startAnimating()
    } else {
        activityIndicator.stopAnimating()
    }
}

在这三个委托方法下面实现：

   func webView(_ webView: WKWebView, didFinish navigation: 
    WKNavigation!) {
    showActivityIndicator(show: false)
}

   func webView(_ webView: WKWebView, didStartProvisionalNavigation 
   navigation: WKNavigation!) {
    showActivityIndicator(show: true)
}

   func webView(_ webView: WKWebView, didFail navigation: 
   WKNavigation!, withError error: Error) {
    showActivityIndicator(show: false)
}

如果它不起作用，请告诉我。