如何找到键盘未覆盖的视图部分 (UIModalPresenationStyleFormSheet)？

Question

我有一个视图控制器显示一个带有 UITextView 的视图，我想在键盘出现时调整视图的大小，以便键盘不会覆盖 UITextView。我几乎在所有情况下都能正常工作。据我所知，我仍然在 iPad 上看到一些奇怪的东西，只有当视图控制器出现在 ModalPresentationStyleFormSheet 中时，而且只有在 LandscapeRight 方向上。

我的视图控制器的 -keyboardWillShow 的相关部分：

// We'll store my frame above the keyboard in availableFrame
CGRect availableFrame = self.view.frame;

// Find the keyboard size
NSDictionary *userInfo = [notification userInfo];
NSValue keyboardFrameScreenValue = userInfo[UIKeyboardFrameBeginUserInfoKey];
CGRect keyboardFrameScreen =  [keyboardFrameScreenValue CGRectValue];
CGRect keyboardFrame = [self.view convertRect:keyboardFrameScreen fromView:nil];
CGSize keyboardSize = keyboardFrame.size;

// Figure out how much of my frame is covered by the keyboard
CGRect screenBounds = [self.view convertRect:[UIScreen mainScreen].bounds
                                    fromView:nil];
CGRect myBoundsScreen = [self.view boundsInWindow]; // See below
CGFloat myBottom = myBoundsScreen.origin.y + myBoundsScreen.size.height;
CGFloat keyboardTop = screenBounds.size.height - keyboardSize.height;
CGFloat lostHeight = myBottom - keyboardTop;
availableFrame.size.height -= lostHeight;

-[UIView boundsInWindow]:

- (CGRect)boundsInWindow {
  UIInterfaceOrientation orientation =
    [UIApplication sharedApplication].statusBarOrientation;
  CGRect bounds = [self convertRect:self.bounds toView:self.window];
  if (UIInterfaceOrientationIsLandscape(orientation)) {
    // Swap origin
    CGFloat x = bounds.origin.y;
    bounds.origin.y = bounds.origin.x;
    bounds.origin.x = x;
    // Swap size
    CGFloat width = bounds.size.height;
    bounds.size.height = bounds.size.width;
    bounds.size.width = width;
  }

  return bounds;
}

这在大多数情况下都有效。但是，当我的应用程序处于用户界面方向 LandscapeRight 时，我从 -boundsInWindow 获得的原点比应有的要低很多。什么可能导致这种情况？

感谢您的任何帮助！

Answer 1

威尔的回答是正确的想法，但我不得不对其进行一些调整以使其正确

extension UIView {
    func heightCoveredByKeyboardOfSize(keyboardSize: CGSize) -> CGFloat {
        let frameInWindow = convertRect(bounds, toView: nil)
        guard let windowBounds = window?.bounds else { return 0 }

        let keyboardTop = windowBounds.size.height - keyboardSize.height
        let viewBottom = frameInWindow.origin.y + frameInWindow.size.height

        return max(0, viewBottom - keyboardTop)
    }
}