UIView的高度约束动画

Question

我有名为DetailView的UIView，它具有以下约束：

DetailView.top = top
DetailView.trailing = Safe Area.trailing
DetailView.leading = Safe Area.leading
height = 295

全部在StoryBoard中制作。 DetailView是图像上的这个灰色矩形

我想在点击按钮后更改此UIView的高度，所以我有IBAction来实现这一点

@IBAction func detailViewTapped(_ sender: Any) {
        if detailViewHeightConstraint.constant < 500 {
            detailViewHeightConstraint.constant = 523
            UIView.animate(withDuration: 0.5) {
                self.detailView.layoutIfNeeded()
            }
            arrowImageView.image = UIImage(named: "up-arrow")
        } else {
            detailViewHeightConstraint.constant = 295
            UIView.animate(withDuration: 0.5) {
                self.detailView.layoutIfNeeded()
            }
            arrowImageView.image = UIImage(named: "down-arrow")
        }
    }

更改尺寸效果完美，但动画效果不佳。 我想达到扩展到底部的效果，但是动画在屏幕之间开始，然后扩展到底部和顶部。 在此图片上可以看到动画的开始如何获得理想的效果？

Answer 1

动画主视图

 @IBAction func detailViewTapped(_ sender: Any) {
    if detailViewHeightConstraint.constant < 500 {
        detailViewHeightConstraint.constant = 523
        UIView.animate(withDuration: 0.5) {
            self.view.layoutIfNeeded()
        }
        arrowImageView.image = UIImage(named: "up-arrow")
    } else {
        detailViewHeightConstraint.constant = 295
        UIView.animate(withDuration: 0.5) {
            self.view.layoutIfNeeded()
        }
        arrowImageView.image = UIImage(named: "down-arrow")
    }
}