Ios 显示键盘时管理UIScrollView内容

在教程中，当键盘出现时移动文本字段所需的代码就在这里。但是，代码不会检查键盘上的字符是否与文本字段重叠。奇怪的是，即使没有代码检查键盘和文本字段的重叠，它也能工作。当键盘与文本字段重叠时，滚动视图向上移动；当键盘与文本字段不重叠时，滚动视图不移动

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
  }

  deinit {
NSNotificationCenter.defaultCenter().removeObserver(self)
}

  func keyboardWillShow(notification: NSNotification) {
adjustInsetForKeyboardShow(true, notification: notification)
   }

func keyboardWillHide(notification: NSNotification) {
adjustInsetForKeyboardShow(false, notification: notification)
}

  func adjustInsetForKeyboardShow(show: Bool, notification: NSNotification) {
let userInfo = notification.userInfo ?? [:]
let keyboardFrame = (userInfo[UIKeyboardFrameBeginUserInfoKey] as NSValue).CGRectValue()
let adjustmentHeight = (CGRectGetHeight(keyboardFrame) - CGRectGetHeight(navigationController!.toolbar.frame) + 20) * (show ? 1 : -1)

fgScrollView.contentInset.bottom += adjustmentHeight
fgScrollView.scrollIndicatorInsets.bottom += adjustmentHeight

println("\(fgScrollView.contentInset.bottom)")
  }

在苹果开发者网站上做了一些研究之后，我发现苹果确实使用了一些代码来检查重叠是否发生。 代码如下所示

// If active text field is hidden by keyboard, scroll it so it's visible
// Your app might not need or want this behavior.
CGRect aRect = self.view.frame;
aRect.size.height -= kbSize.height;
if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
    [self.scrollView scrollRectToVisible:activeField.frame animated:YES];
}

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请解释为什么示例代码不需要进行检查？

您可能需要检查此库我不擅长swift，但它看起来好像添加了一些delta hightOfKeybord，然后滚动到它。无论如何，为什么不尝试在Xcode中调试视图呢。