Let's say I have a UIWebView with some javascript functions. I want those javascript functions to be able to request information from my app and my app should return it. I am able to get the requests using URL Schemes however, I don't know how to return the information back to the javascript function.

Is injecting a javascript variable into the UIWebView, then calling the javascript function again with the variable as a parameter the best way to do it? Or are there methods I can use for UIWebView?

• javascript
• iphone
• objective-c

Use asynchronous communication. Have a Javascript function for the Objective C routine to call back into the Javascript with any reply parameters required. The Javascript callback function can even be one of the parameters sent to Objective C code via a URL scheme.

Injecting Javascript via stringByEvaluatingJavaScriptFromString is absolutely fine.

The other direction would be better handled via webView:shouldStartLoadWithRequest:navigationType:

How to Properly Call ObjectiveC From Javascript (incl. Callback to JS) describes it in detail, sources are included.

Sample JS-code which makes use of the Objective-C returnValue:

NativeBridge.call("objCMethod", ["firstArgument"], function (returnValue) {
    if (returnValue) {
      // whatever
    } else {
      // whatever
    }
});