尝试以编程方式选择 UIWebView 中的文本时，setStart 和 setEnd 抛出错误

setStart and setEnd throwing error when trying to programmatically select text in UIWebView(尝试以编程方式选择 UIWebView 中的文本时，setStart 和 setEnd 抛出错误)

问题描述

这是我在 UIWebView 中使用的一些 HTML:

点击链接后，我想以编程方式选择 UIWebView 中的链接文本(因此这是一个链接"现在将使用蓝色的 iOS 文本选择工具突出显示).这就是我在 a 标签的 href 中发送一些范围信息的原因.这是我用来尝试进行编程选择的调用:

//设置内容可编辑 true[self.webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"selectElementContentsInRange(document.getElementById('1'), 10, 20)"]];

这是javascript函数:

function selectElementContentsInRange(el, first, second) {var range = document.createRange();alert("在这里做");range.setStart(el.firstChild, first);alert("这里不行");range.setEnd(el.firstChild, second);var sel = window.getSelection();sel.removeAllRanges();sel.addRange(范围);}

正如您在警报中看到的那样，它不会通过 range.setStart() 调用而不会引发错误.Safari javascript 调试器给了我这个错误:

IndexSizeError:DOM 异常 1:索引或大小为负数，或大于允许值.

我尝试了很多不同的方法，但没有任何效果.我完全不知所措，非常感谢您对如何做到这一点的一些见解.我开始怀疑是否有可能以编程方式在 UIWebView 中选择文本.我错了吗?有人做过吗?

问题是你试图在 <div> 元素的第一个子节点中设置范围的边界，如果您的 HTML 确实看起来像问题中的那样，它要么是一个纯空格文本节点，要么是 <span> 元素，如果你的实际 HTML 中没有空格.在后一种情况下，即在元素中设置范围边界，偏移量表示边界之前元素的子节点数.

Here is some HTML that I am working with in my UIWebView:

<div id = "1">
    <span style = "background-color:red">
         <a href = "10&20">
              This is a link
         </a>
    </span>
</div>

Once the link is tapped, I want to programmatically select the link text in the UIWebView (so "This is a link" would now be highlighted with the blue iOS text selection tool). This is why I am sending some range information in the href of the a tag. This is the call I am using to try and make this programmatic selection:

//set content editable true
[self.webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"selectElementContentsInRange(document.getElementById('1'), 10, 20)"]];

And this is the javascript function:

function selectElementContentsInRange(el, first, second) {
    var range = document.createRange();
    alert("Makes it here");
    range.setStart(el.firstChild, first);
    alert("Doesn't make it here");
    range.setEnd(el.firstChild, second);

    var sel = window.getSelection();
    sel.removeAllRanges();
    sel.addRange(range);
}

And as you can see with the alerts, it doesn't make it past the range.setStart() call without throwing an error. The Safari javascript debugger is giving me this error:

IndexSizeError: DOM Exception 1: Index or size was negative, or greater than the allowed value.

I have tried so many different things, and nothing is working. I am completely at my wits end and would really appreciate some insight into how to do this. I am beginning to doubt that it is even possible to programmatically select text in UIWebView. Am I wrong? Has anyone done this?

The problem is that you're trying to set the range's boundaries in the first child node of the <div> element, which is either a white space-only text node if your HTML really does look like it does in the question, or the <span> element if there is no white space in your actual HTML. In the latter case, i.e. setting a range boundary in an element, the offset represents the number of child nodes of the element preceding the boundary.