尝试以编程方式在UIWebView中选择文本时，setStart和setEnd抛出错误 [英] setStart and setEnd throwing error when trying to programmatically select text in UIWebView

问题描述

以下是我在UIWebView中使用的一些HTML：

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>

点击链接后，我想以编程方式选择UIWebView中的链接文本（所以这个是一个链接现在将使用蓝色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此程序化选择的电话：

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)"]];

这是javascript函数：

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);
}

正如您可以看到警报一样，它不会过去 range.setStart（）调用而不会抛出错误。 Safari javascript调试器给出了这个错误：

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.

我尝试过很多不同的东西，但没有任何效果。我完全在我的智慧结束，并真的很感激有关如何做到这一点的一些见解。我开始怀疑甚至可以在UIWebView中以编程方式选择文本。我错了吗？有没有人这样做过？

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?

推荐答案

问题是你试图在第一个子节点中设置范围的边界< div> 元素，如果您的HTML确实看起来像在问题中那样，则为纯空格文本节点，或如果实际HTML中没有空格，则< span> 元素。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。

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.

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