ios - 在编辑时将 TextView 保持在键盘上方

Question

我有一个动态高度的 TextView 。当用户添加或删除文本时， TextView 的高度会发生变化。

我的问题是，随着用户添加文本和 TextView 的增长，它会在键盘后面消失。当键盘出现时，我已经成功地移动了 View ，因此 TextView 从一开始就被隐藏了，但是我似乎无法弄清楚如何在高度变化时将它保持在键盘上方。非常感谢任何帮助!

键盘出现和消失时移动 View 的函数:

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
}

Answer 1

因此，需要发生的事情是，只要光标位置发生变化(如果它在边界之外)，就需要告知包含 scrollView 的内容进行滚动。我已经从链接中改编了一个函数来调用它。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)
}