return value javascript UIWebView

Question

i\'m trying to get the return value of a javascript function(for example: return \"hello\") with iPhone SDK.

On OS X the WebView method -stringByE

Answer 1

I had the same problem when I tried call some functions from google maps API.

There was a problem with returning objects, so I solved it by function toString().

NSString *result = [webView stringByEvaluatingJavaScriptFromString:
                @"map.getBounds().toString();"];

Answer 2

The return string is the result of the last Javascript statement. Do not put return in front of it!

The minimum code that worked for me:

UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectZero];
[self.view addSubview:webView];
NSString *result = [webView stringByEvaluatingJavaScriptFromString:
                    @"function f(){ return \"hello\"; } f();"];
NSLog(@"result: '%@'", result); // 'hello'
[webView release];

So I had to add the UIWebView* to a view (otherwise it would crash afterwards), but didn't have to load anything into the webview.

Notice that the last statement is just "f();", so the returned string will contain the result of the evaluation of f().