在UIWebView的"Start Load"回调中破解了JavaScript

Ed *_*nus 6 iphone uiwebview iphone-sdk-3.0

我试图在页面的onLoad事件触发之前执行一些JS.

但我无法成功调用stringByEvaluatingJavaScriptFromStringwebViewDidStartLoad委托方法.

要重现此问题,您可以使用以下代码.

代表实施:

-(void)webViewDidStartLoad:(UIWebView *)webView {
    [webView stringByEvaluatingJavaScriptFromString:@"window.valueHasBeenSet=true"];
}
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查看此HTML:

<html>
<head></head>
<body>

<script type="text/javascript" charset="utf-8">
    if (window.valueHasBeenSet)
    {
        // We enter this branch the first time
        document.write('<h3>Everything is OK. Value has been set.</h3>');
    }
    else
    {
        // We incorrectly enter this branch on reloads
        document.write('<h3>Error. Value has not been set.</h3>');
    }
</script>

<a href="javascript:window.location.reload()">Reload</a>

</body>
</html>
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此页面适用于第一个视图("一切正常".),但无论重新加载方法如何,都会在所有重新加载时失败.正如您可能期望的那样,这在shouldStartLoadWithRequest委托中也不起作用.

我也试过立即执行JavaScript以下webViewDidStartLoadperformSelector:withObject:afterDelay:0,但无济于事.

有任何想法吗?

小智 1

我设法使用 NSTimer 让它工作

- (void)viewDidLoad {
    timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(update) userInfo:nil repeats:YES];
}

-(void)update{
    if (Progress.progress <= 1.0) {
        [website stringByEvaluatingJavaScriptFromString:@"window.valueHasBeenSet=true"];
    }
}
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