swift - 每当用户移动到其他页面时如何从 webview 获取 url

Question

每当 URL 更改时，如何从 webView 获取 URL？

我想在当前 URL 更改时更改按钮颜色。所以我需要一直检查当前的 URL。

而且我还想获​​取字符串形式的 URL 值。

我尝试了下面的代码，但它根本不起作用。

NotificationCenter.default.addObserver(self, selector: #selector(urlChecker), name: NSNotification.Name.NSURLCredentialStorageChanged, object: webView)

Answer 1

你可以使用:

1。解决方案

UIWebViewDelegate

https://developer.apple.com/reference/uikit/uiwebviewdelegate/1617945-webview

optional func webView(_ webView: UIWebView, 
  shouldStartLoadWith request: URLRequest, 
       navigationType: UIWebViewNavigationType) -> Bool

UIWebViewNavigationType:

https://developer.apple.com/reference/uikit/uiwebviewnavigationtype

不要忘记返回true

case linkClicked

User tapped a link.

case formSubmitted

User submitted a form.

case backForward

User tapped the back or forward button.

case reload

User tapped the reload button.

case formResubmitted

User resubmitted a form.

case other

Some other action occurred.

2。解决方案

注入(inject) Javascript JavaScript MessageHandler

(归功于Vasily Bodnarchuk)

解决方案在这里:https://stackoverflow.com/a/40730365/1930509

Swift 3 example.

Description

The script is inserted into page which will displayed in WKWebView. This script will return the page URL (but you can write another JavaScript code). This means that the script event is generated on the web page, but it will be handled in our function:

func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {...}

Full Code example

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {

    var webView = WKWebView()
    let getUrlAtDocumentStartScript = "GetUrlAtDocumentStart"
    let getUrlAtDocumentEndScript = "GetUrlAtDocumentEnd"

     override func viewDidLoad() {
             super.viewDidLoad()

            let config = WKWebViewConfiguration()
            config.addScript(script: WKUserScript.getUrlScript(scriptName: getUrlAtDocumentStartScript),
 scriptHandlerName:getUrlAtDocumentStartScript, scriptMessageHandler:
 self, injectionTime: .atDocumentStart)
            config.addScript(script: WKUserScript.getUrlScript(scriptName: getUrlAtDocumentEndScript),
scriptHandlerName:getUrlAtDocumentEndScript, scriptMessageHandler:
self, injectionTime: .atDocumentEnd)


             webView = WKWebView(frame:  UIScreen.main.bounds, configuration: config)
            webView.navigationDelegate = self
             view.addSubview(webView)
        }

     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
         webView.loadUrl(string: "http://apple.com")
    }
}

extension ViewController: WKScriptMessageHandler {
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        switch message.name {

            case getUrlAtDocumentStartScript:
                print("start: \(message.body)")

            case getUrlAtDocumentEndScript:
                print("end: \(message.body)")

            default:
                break;
        }
    }
}

extension WKUserScript {
    class func getUrlScript(scriptName: String) -> String {
        return "webkit.messageHandlers.\(scriptName).postMessage(document.URL)"
    }
}

extension WKWebView {
    func loadUrl(string: String) {
        if let url = URL(string: string) {
            load(URLRequest(url: url))
        }
    }
}

 extension WKWebViewConfiguration {
        func addScript(script: String, scriptHandlerName:String, scriptMessageHandler: WKScriptMessageHandler,injectionTime:WKUserScriptInjectionTime) {
             let userScript = WKUserScript(source: script, injectionTime: injectionTime, forMainFrameOnly: false)
             userContentController.addUserScript(userScript)
             userContentController.add(scriptMessageHandler, name: scriptHandlerName)
        }
    }

Info.plist

add in your Info.plist transport security setting

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

Result

Resources ##

Document Object Properties and Methods