ios - 更改高度时，UITextView 的 textContainer 在错误的帧处呈现
<p><p>我想要的只是在您键入/粘贴时调整 <code>UITextView</code> 的大小。它应该是可滚动的，因为我不希望 <code>UITextView</code> 填满屏幕。用这几行代码就可以轻松实现。</p>
<pre><code>@IBOutlet weak var mainTextView: UITextView!
@IBOutlet weak var mainTextViewHeightConstraint: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
self.mainTextView.delegate = self
}
// This method is used for calculating the string's height in a UITextField
func heightOf(text: String, for textView: UITextView) -> CGFloat {
let nsstring: NSString = text as NSString
let boundingSize = nsstring.boundingRect(
with: CGSize(width: textView.frame.size.width, height: .greatestFiniteMagnitude),
options: .usesLineFragmentOrigin,
attributes: [.font: textView.font!],
context: nil).size
return ceil(boundingSize.height + textView.textContainerInset.top + textView.textContainerInset.bottom)
}
// This method calculates the UITextView's new height
func calculateHeightFor(text: String, in textView: UITextView) -> CGFloat {
let newString: String = textView.text ?? ""
let minHeight = self.heightOf(text: "", for: textView) // 1 line height
let maxHeight = self.heightOf(text: "\n\n\n\n\n", for: textView) // 6 lines height
let contentHeight = self.heightOf(text: newString, for: textView) // height of the new string
return min(max(minHeight, contentHeight), maxHeight)
}
// The lines inside will change the UITextView's height
func textViewDidChange(_ textView: UITextView) {
self.mainTextViewHeightConstraint.constant = calculateHeightFor(
text: textView.text ?? "",
in: textView)
}
</code></pre>
<p>这非常有效，除非您粘贴多行文本，或按 <strong>enter</strong>(换行符)。</p>
<hr/>
<p>为了解决粘贴问题，各种 SO 问题建议我创建 <code>UITextView</code> 的子类来覆盖 <code>paste(_:)</code> 方法，或者我使用 <code>textView(_: shouldChangeTextIn....)</code> 委托(delegate)方法。经过几次实验，最好的答案是使用 <code>shouldChangeTextIn</code> 方法，这导致我的代码变成了这个</p>
<pre><code>// I replaced `textViewDidChange(_ textView: UITextView)` with this
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
self.mainTextViewHeightConstraint.constant = calculateHeightFor(
text: ((textView.text ?? "") as NSString).replacingCharacters(in: range, with: text),
in: textView)
return true
}
</code></pre>
<hr/>
<p>现在应该发生的是，当您粘贴文本时，<code>UITextView</code> 应该如下所示。 (粘贴的字符串是“A\nA\nA\nA\nA”或 5 行只是 A)</p>
<p> <a href="/image/zpAth.png" rel="noreferrer noopener nofollow"><img src="/image/zpAth.png" alt="enter image description here"/></a> </p>
<p>可是变成了这个样子</p>
<p> <a href="/image/6uFSu.png" rel="noreferrer noopener nofollow"><img src="/image/6uFSu.png" alt="enter image description here"/></a> </p>
<p>从截图中可以看出，textContainer 的框架在错误的位置。现在奇怪的是，它似乎只在你粘贴到一个空的 <code>UITextView</code> 时才会发生。</p>
<p>我尝试过设置和重置 <code>UITextView</code> 的 frame.size，我尝试过手动设置 <code>NSTextContainer</code> 的大小以及其他一些 hacky 解决方案，但是我似乎无法修复它。我该如何解决这个问题？</p>
<p>附加信息:</p>
<p>查看 View 调试器后，输入 <strong>enter</strong>(换行符)时的外观如下所示</p>
<p> <a href="/image/gdf1N.png" rel="noreferrer noopener nofollow"><img src="/image/gdf1N.png" alt="enter image description here"/></a>
<a href="/image/ivQRM.png" rel="noreferrer noopener nofollow"><img src="/image/ivQRM.png" alt="enter image description here"/></a> </p>
<p>如我们所见，文本容器的位置错误。</p>
<hr/>
<p>毕竟添加 <code>UIView.animate</code>block 似乎解决了一些问题，但不是全部。为什么会这样？</p>
<pre><code>// These snippet kind of fixes the problem
self.mainTextViewHeightConstraint.constant = calculateHeightFor(
text: textView.text ?? "",
in: textView)
UIView.animate(withDuration: 0.1) {
self.view.layoutIfNeeded()
}
</code></pre>
<p>注意:我没有放置 <code>UIView.animate</code> 解决方案，因为它没有涵盖所有的错误。</p>
<p><strong>注意:</strong></p>
<p>操作系统支持:iOS 8.xx - iOS 12.xx
Xcode:v10.10
Swift:3 和 4(我都试过了)</p>
<p><strong>PS:</strong>是的，我已经处理过其他一些 SO 问题，例如底部列出的问题和其他一些问题</p>
<ul>
<li> <a href="https://stackoverflow.com/questions/32913105/textcontainer-isnt-resizing-while-changing-bounds-of-uitextview" rel="noreferrer noopener nofollow">TextContainer isn't resizing while changing bounds of UITextView</a> </li>
<li> <a href="https://stackoverflow.com/questions/21889657/uitextviews-text-going-beyond-bounds" rel="noreferrer noopener nofollow">UITextView's text going beyond bounds</a> </li>
<li> <a href="https://stackoverflow.com/questions/51770900/uitextview-stange-animation-glitch-on-paste-action-ios11" rel="noreferrer noopener nofollow">UITextView stange animation glitch on paste action (iOS11)</a> </li>
<li> <a href="https://stackoverflow.com/questions/39268477/how-to-calculate-textview-height-base-on-text" rel="noreferrer noopener nofollow">How to calculate TextView height base on text</a> </li>
</ul></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>可以忽略所有计算高度的代码，使用设置textview属性scrolling Enabled = false
textview 将自行调整以适应文本内容
<a href="/image/wUGtg.png" rel="noreferrer noopener nofollow">image1</a> </p>
<p>然后根据需要更改代码</p>
<pre><code>@IBOutlet weak var textView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
self.textView.text = "A\nA\nA\nA\nA"
}
</code></pre>
<p>结果会是这样
<a href="/image/gvG8c.png" rel="noreferrer noopener nofollow">image2</a> </p></p>
<p style="font-size: 20px;">关于ios - 更改高度时，UITextView 的 textContainer 在错误的帧处呈现，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/53206469/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/53206469/
</a>
</p>
页:
[1]