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我正在使用自定义 UIPresentationController 以模态方式呈现视图。呈现视图后，呈现视图中的第一个文本字段成为第一响应者，并且键盘出现。为了确保视图仍然可见，我将其向上移动。但是，当我这样做时，frameOfPresentedViewInContainerView它不再与视图的实际框架匹配。因此，当我点击视图时，它会被关闭，因为 backgroundView 上有一个 tapGestureRecogziner，它位于 presentingView 的顶部。如何通知presentingControllerpresentingView的frame/position发生了变化？

在 UIPresentationController 中：

    override var frameOfPresentedViewInContainerView: CGRect {
        var frame =  CGRect.zero
        let safeAreaBottom = self.presentingViewController.view.safeAreaInsets.bottom
        guard let height = presentedView?.frame.height else { return frame }
        if let containerBounds = containerView?.bounds {
            frame = CGRect(x: 0,
                           y: containerBounds.height - height - safeAreaBottom,
                           width: containerBounds.width,
                           height: height + safeAreaBottom)
        }
        return frame
    }

    override func presentationTransitionWillBegin() {
        if let containerView = self.containerView, let coordinator = presentingViewController.transitionCoordinator {
            containerView.addSubview(self.dimmedBackgroundView)
            self.dimmedBackgroundView.backgroundColor = .black
            self.dimmedBackgroundView.frame = containerView.bounds
            self.dimmedBackgroundView.alpha = 0
            coordinator.animate(alongsideTransition: { _ in
                self.dimmedBackgroundView.alpha = 0.5
            }, completion: nil)
        }
    }

以模态方式呈现视图：

            let overlayVC = CreateEventViewController()

            overlayVC.transitioningDelegate = self.transitioningDelegate
            overlayVC.modalPresentationStyle = .custom
            self.present(overlayVC, animated: true, completion: nil)

键盘出现时的动画（在呈现的视图中）：

    @objc func animateWithKeyboard(notification: NSNotification) {
        let userInfo = notification.userInfo!
        guard let keyboardHeight = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue.height,
            let duration = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as? Double,
            let curve = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? UInt else {
                return
        }

        // bottomContraint is the constraint that pins content to the bottom of the superview.
        let moveUp = (notification.name == UIResponder.keyboardWillShowNotification)
        bottomConstraint.constant = moveUp ? (keyboardHeight) : originalBottomValue

        let options = UIView.AnimationOptions(rawValue: curve << 16)
        UIView.animate(withDuration: duration, delay: 0,
                       options: options,
                       animations: {
                        self.view.layoutIfNeeded()
        }, completion: nil)
    }
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1 回答 1

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从苹果文档：

UIKit 在演示过程中多次调用此方法，因此您的实现应该每次都返回相同的框架矩形。不要使用此方法更改视图层次结构或执行其他一次性任务。

AFAIK，如果您通过此变量指定框架，建议不要在整个演示过程中更改它。如果您打算使用帧，请不要指定此变量并在动画师中手动处理所有更改

于 2019-07-17T10:02:43.577 回答