Invoke method in objective c code from HTML code using UIWebView

Question

I have .html file in my iOS app. HTML file has few div blocks with onClick methods. When I tap on these blocks I invoke some javascript code in web view, but I need also know about these events in my source code.

For example when I tap on web element and onClick is called I need to invoke some method in the code e.g. - (void)didTouchedWebElementWithId

Can I do this stuff. Thanks.

Community · Accepted Answer · 2017-05-23 11:54:41Z

48

To call method of Objective-C in JS:

the below url helps in doing that

How to invoke Objective C method from Javascript and send back data to Javascript in iOS?

There is no way of executing, we make workaround by a navigation to other page and during the navigation, a webview delegate will watch for prefix of the navigation and execute the method we specified.

sample.html

<html>
    <head>
        <script type='text/javascript'>
            function getText()
            {
                return document.getElementById('txtinput').value;
            }
            function locationChange()
            {
                window.location = 'ios:webToNativeCall';
            }
        </script>
    </head>
    <body style='overflow-x:hidden;overflow-y:hidden;'>
        <h2 style = "font-size:16px;" align='center'>Hi Welcome to Webpage</h2>
        <br/>
        <p align='center' style = "font-size:12px;">Please Click the button after entering the text</p>
        <br/>
        <center>
            <input type='text' style='width:90px;height:30px;' id='txtinput'/>
        </center>
        <br/>
        <center>
            <input type='button' style='width:90px;height:30px;' onclick='locationChange()' value='click me'>
        </center>
    </body>
</html>

Objective-C code

when you click button in html page the below delegate will fired and navigation cancelled because we return NO and respective method is called

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
    if ([[[request URL] absoluteString] hasPrefix:@"ios:"]) {

        // Call the given selector
        [self performSelector:@selector(webToNativeCall)];        
        // Cancel the location change
        return NO;
    }
    return YES;
}

- (void)webToNativeCall
{
    NSString *returnvalue =  [self.webviewForHtml stringByEvaluatingJavaScriptFromString:@"getText()"];

    self.valueFromBrowser.text = [NSString stringWithFormat:@"From browser : %@", returnvalue ];
}

edited May 23, 2017 at 11:54

CommunityBot

11 silver badge

answered Mar 21, 2013 at 7:19

Vinodh

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7 Comments

Gustav Over a year ago

Beware of the security implications!

Vinodh Over a year ago

can you be more detail about it ?

Gustav Over a year ago

suppose you have a method called getSecretToken in your class. Then you could call it from Javascript

Soumya Ranjan Over a year ago

Thanks Bro...Its really a awesome answer. I stucked from last 2 days. I already post my q but didn't get any valuable solution. Finally your answer solved my problem... So much thanks

Ankita Shah Over a year ago

How can I use this for getting value from server to native method call?

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