html – 如何允许缩放UIWebView(尝试过所有内容)

Apple说：
scalesPageToFit
如果是,则缩放网页以适应并且用户可以放大和缩小.如果为NO,则禁用用户缩放.默认值为NO.
>如果您查看页面的来源,您应该能够找到// Meta name =“viewport”content =“width = device-width; initial-scale = 1.0; maximum-scale = 1.0;”//.

为了向您显示缩放效果.我想用以下代替：
// Meta name =“viewport”content =“width = device-width; initial-scale = 1.0; maximum-scale = 5.0; user-scalable = 1;”//.
>为UIWebview的方法运行以下javascript：StringByEvaluaTingJavaScriptFromString：in – (void)webViewDidFinishLoad：(UIWebView *)webView {
}

function setScale(){
var all_Metas=document.getElementsByTagName('Meta');
if (all_Metas){
    var k;
    for (k=0; k<all_Metas.length;k++){
        var Meta_tag=all_Metas[k];
        var viewport= Meta_tag.getAttribute('name');
        if (viewport&& viewport=='viewport'){
            Meta_tag.setAttribute('content',"width=device-width; initial-scale=1.0; maximum-scale=5.0; user-scalable=1;");
        }

    }
}    
}