当编辑文本时，保持文本视图在键盘上方

Question

当编辑文本时，保持文本视图在键盘上方

4

我有一个高度动态的文本视图。当用户添加或删除文本时，文本视图的高度会改变。

我的问题是，当用户添加文本并且文本视图增长时，它会消失在键盘后面。我已成功移动了视图以在键盘出现时隐藏文本视图，但我似乎无法弄清如何在高度改变时将其保持在键盘之上。非常感谢任何帮助！

移动视图的函数在键盘出现和消失时：

func keyboardWillShow(sender: NSNotification) {
    let info: NSDictionary = sender.userInfo!
    let value: NSValue = info.valueForKey(UIKeyboardFrameBeginUserInfoKey) as! NSValue
    let keyboardSize: CGSize = value.CGRectValue().size
    let contentInsets: UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardSize.height + 20, 0.0)
    scrollView.contentInset = contentInsets

    var aRect: CGRect = self.view.frame
    aRect.size.height -= keyboardSize.height
    let activeTextFieldRect: CGRect? = activeItemRect()
    let activeTextFieldCentre: CGPoint? = CGPointMake(CGRectGetMidX(activeTextFieldRect!), CGRectGetMidY(activeTextFieldRect!))
    if (!CGRectContainsPoint(aRect, activeTextFieldCentre!)) {
        scrollView.scrollRectToVisible(activeTextFieldRect!, animated:true)
    }
}

func keyboardWillHide(sender: NSNotification) {
    let contentInsets: UIEdgeInsets = UIEdgeInsetsZero
    scrollView.contentInset = contentInsets
}

- 01Riv

你的textView包含在哪里？如果它是一个tableView，请参考https://dev59.com/W2Ml5IYBdhLWcg3we283 - sschale

这不是一个表格视图。文本字段是内容视图的子视图，而内容视图是滚动视图的子视图，滚动视图位于原始视图内部。谢谢！ - 01Riv

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- sschale · Accepted Answer

因此，需要在光标位置超出边界时告诉包含 scrollView 滚动。我从链接中改编了一个函数来调用此操作。请确保将 scrollView 替换为您的名称。

internal func scrollToCursorForTextView(textView: UITextView) {
    var cursorRect = textView.caretRectForPosition(textView.selectedTextRange!.start)
    cursorRect = scrollView.convertRect(cursorRect, fromView: textView)
    if !self.rectVisible(cursorRect) {
      cursorRect.size.height += 8
      scrollView.scrollRectToVisible(cursorRect, animated: true)
    }
}

internal func rectVisible(rect: CGRect) -> Bool {
    var visibleRect = CGRect()
    visibleRect.origin = scrollView.contentOffset
    visibleRect.origin.y += scrollView.contentInset.top
    visibleRect.size = scrollView.bounds.size
    visibleRect.size.height -= scrollView.contentInset.top + scrollView.contentInset.bottom
    return CGRectContainsRect(visibleRect, rect)
}

Swift 4 更新

internal func scrollToCursorForTextView(textView: UITextView) {
    guard let startOfRange = textView.selectedTextRange?.start else { return }
    var cursorRect = textView.caretRect(for: startOfRange)
    cursorRect = scrollView.convert(cursorRect, from: textView)
    if !rectVisible(rect: cursorRect) {
        cursorRect.size.height += 8
        scrollView.scrollRectToVisible(cursorRect, animated: true)
    }
}

func rectVisible(rect: CGRect) -> Bool {
    var visibleRect = CGRect()
    visibleRect.origin = scrollView.contentOffset
    visibleRect.origin.y += scrollView.contentInset.top
    visibleRect.size = scrollView.bounds.size
    visibleRect.size.height -= scrollView.contentInset.top + scrollView.contentInset.bottom
    return visibleRect.contains(rect)
}