Inject Custom CSS and javascript into WebView

Question

How can I inject custom CSS into a WebView like changing the background-color: of http://www.apple.com/. Javascript would also be nice because in the future I would like to have control of the javascript.

Community · Accepted Answer · 2017-05-23 12:03:55Z

2

The best way would be the one delineated by Rob Keniger, with this answer: https://stackoverflow.com/a/2475623/307881. This technique should also work for javascript. If it doesn't work off the bat try modifying the DOM after the WebView has finished loading (see below)

You can also directly evaluate a javascript string without accessing the DOM.

First, get your javascript string, then, when your WebView finishes loading its content, use the delegate method of WebFrameLoadDelegate:

- (void)webView:(WebView *)sender didFinishLoadForFrame:(WebFrame *)frame {
    [sender stringByEvaluatingJavaScriptFromString:jsStringToInject];
}

edited May 23, 2017 at 12:03

CommunityBot

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answered Jul 31, 2012 at 3:18

Vervious

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7 Comments

atomikpanda Over a year ago

the CSS part woks but not the JS

Vervious Over a year ago

Did you try using stringByEvaluatingJavaScriptFromString? Or do both methods not work?

Vervious Over a year ago

Do you get any errors? I currently use the second method and it works well - what javascript are you trying to embed?

atomikpanda Over a year ago

I don't get any errors i'm just trying to test it using the js: alert('Hello World!');

Vervious Over a year ago

Well, alert() has never worked for me in a WebView. Maybe stringByEvaluatingString doesn't support it.

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