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 -stringByEvaluatingJavaScriptFromString returns a NSString containing the js function return value, but on the iPhone no value is returned.

How can I solve this?

I found a private UIWebViewDelegate method

- (void)webView:(id)fp8 runJavaScriptAlertPanelWithMessage:(id)fp12 initiatedByFrame:(id)fp16

invoked when the alert() function is used in the js script. So I can get the "return" value just by calling alert(myReturValue).

That doesn't solve my problem, because I need something in the public SDK.

user42690 · Accepted Answer · 2009-02-03 03:24:41Z

29

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().

answered Feb 3, 2009 at 3:24

user42690

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bendewer · Accepted Answer · 2010-06-24 10:11:28Z

6

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();"];

answered Jun 24, 2010 at 10:11

bendewer

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1 Comment

Navnath Memane Over a year ago

can you answer this too stackoverflow.com/questions/10793698/…

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