using KVO to observe WKWebView's URL property not work in iOS 10

Question

I use WKWebView to load my webpage. When user click a button in webpage, my webpage will open a custom schema URL (e.g. asfle://download?media_id=1). And I use KVO to obser

Answer 1

You can still observe WKWebView's url property, just be sure to hold a strong reference to the returned observation:

class ViewController: UIViewController {
    var webView: WKWebView!
    var urlObservation: NSKeyValueObservation?

    override func viewDidLoad() {
        super.viewDidLoad()

        // ...Initialize web view.
        webView = WKWebView(frame: view.bounds, configuration: WKWebViewConfiguration())
        webView.autoresizingMask = [.flexibleHeight, .flexibleWidth]
        view.addSubview(webView)

        // Add observation.
        urlObservation = webView.observe(\.url, changeHandler: { (webView, change) in
            NSLog("Web view URL changed to \(webView.url?.absoluteString ?? "Empty")")
        })
    }
}

Also, don't forget to capture self as weak in observation closure if you plan to use it there, as otherwise you will get a retain cycle.