Question

I have an IOS application which has a web browser in it.

When this web browser is displayed, it navigates to a page on Internet, say http://myexample.com/myiosapp.

Is it possible to place a javascript code on this web site, which, when downloaded to phone, communicates with the native application? Can it call an Objective-C method, or write something to storage space of this application?

Ex.
Code hosted on myexample.com/myios app:

function saveSomeString() {
    xcode.Save("somestring");
}

should call an Objective-C function named Save, which saves incoming string parameter to local storage.

Answer 1

Yes, you can, but it is a bit hacky.

On the Objective-C side:

Basically, in the UIWebView, you will use method shouldStartLoadWithRequest (from the UIWebViewDelegate) which is called before a URL request starts:

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType

On Javascript side:

Your javascript code will navigate to a ‘fake’ URL that you will filter on the method above. Something like:

window.location = "js2objc://save:param";

Back on the Objective-C side:

Inside the method I mentioned earlier, you look for the keyword js2objc (or whichever you choose) and then extract the info and take any appropriate action:

if([[url scheme] isEqualToString:@"js2objc"]){
    // extract the parameters and save them, o do whatever action you need
    return NO;  // so the UIWebView doesn't actually follow the url
}