WKWebview观察者

Question

我正在尝试为WKWebview的加载/加载时间添加观察者，但仅在加载时才触发。它永远不会在加载时触发。我在做什么错？

override func viewDidLoad() {
        super.viewDidLoad()

        let url = URL(string: "https://google.com")!
        let request = URLRequest(url:url)
        self.webView.load(request)
        self.webView.addObserver(self, forKeyPath: #keyPath(WKWebView.isLoading), options: .new, context: nil)
    }

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "loading"{
            if webView.isLoading{
                print("loading")
            }
            else{
                print("done")
            }
        }
    }

Answer 1

您必须添加观察之前带有Web视图和KVO中关键路径的任何操作都是字符串，例如

override func viewDidLoad() {
        super.viewDidLoad()
        self.webView.addObserver(self, forKeyPath: "isLoading", 
                                 options: [.new], context: nil)

        let url = URL(string: "https://google.com")!
        let request = URLRequest(url:url)
        self.webView.load(request)
    }

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "isLoading"{
        if webView.isLoading{
            print("loading")
        }
        else{
            print("done")
        }
    }
}