webview改变网页宽度

- (void)webViewDidFinishLoad:(UIWebView *)webView  
{     
    //修改服务器页面的meta的值  
    NSString *meta = [NSString stringWithFormat:@"document.getElementsByName(\"viewport\")[0].content = \"width=%f, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no\"", webView.frame.size.width];  
    [webView stringByEvaluatingJavaScriptFromString:meta];  
}