How to get url from webview whenever user move to other pages - swift

Question

How can I get a URL from webView whenever the URL is changed?
I want to change the button color when current URL is changed. So I need to check the current URL all the time.
And I also would like to get URL value as a String.
I tried the below code but it doesn't work at all.
NotificationCenter.default.addObserver(self, selector: #selector(urlChecker), name: NSNotification.Name.NSURLCredentialStorageChanged, object: webView)

Answer 1

you can use:
1. Solution
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
don't forget to return 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. Solution
Inject Javascript JavaScript MessageHandler
(credit to Vasily Bodnarchuk)
Solution is here: 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