Execute javascript on WKWebView

Question

Created May ’18

Replies 2

Boosts 0

Views 8.0k

Participants 3

Hi, im tryign to execute a javascript line inside of the loaded page on a wkwebview, the line is "document.body.style.backgroundColor = '#212121';". That line will chang the background color of the page.

this is what i tried, its on the ViewDidLoad

chatWebView.evaluateJavaScript("document.body.style.backgroundColor = '#212121';", completionHandler: nil)

they recomended me to add the UIWebViewDelegate but this is wkwebview, and use the webViewDidFinishLoad.

How should i do?

Boost

Answer 1

OOPer OP

May ’18

You can use `WKNavigationDelegate` instead of `UIWebViewDelegate`.

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {
    
    var webView: WKWebView!
    
    override func viewDidLoad() {
        //... assuming the `webView` is setup here
        webView.navigationDelegate = self
        //...
    }
    
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        webView.evaluateJavaScript("document.body.style.backgroundColor = '#212121';", completionHandler: nil)
    }
    
}

0

Answer 2

DTS Engineer OP

Apple

May ’18

they recomended me to add the UIWebViewDelegate but this is wkwebview, and use the webViewDidFinishLoad.

As OOPer pointed out,

WKWebView

has a navigation delegate that you can use for this thing. Another option is to add a

WKUserScript

. Such scripts can be set to run automatically after the document has loaded via the

injectionTime

property.

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