根据按钮动画CAShapeLayer（使用自动布局）

Question

我的按钮正在使用自动布局调整大小。该按钮有一个CAShapeLayer，它的框架设置在layoutSubviews：

var initial = true

override func layoutSubviews() {
    super.layoutSubviews()

    if initial {
        border.frame = layer.bounds
        border.path = UIBezierPath(rect: bounds).CGPath

        initial = false
    }
}

因此，只要更改此按钮的大小，就会立即更改图层而不进行任何动画（隐藏按钮动画本身）。

我试图添加动画：

override func layoutSubviews() {
    super.layoutSubviews()

    func movePosition() {
        let fromValue = border.position.x
        let toValue = center.x

        CATransaction.setDisableActions(true)
        border.position.x = toValue

        let positionAnimation = CABasicAnimation(keyPath: "position.x")
        positionAnimation.fromValue = fromValue
        positionAnimation.toValue = toValue
        positionAnimation.duration = 0.5

        border.addAnimation(positionAnimation, forKey: "position")
    }

    func changesWidth() {
        let fromValue = border.frame.size.width
        let toValue = layer.bounds.width

        CATransaction.setDisableActions(true)
        border.frame.size.width = toValue

        let widthAnimation = CABasicAnimation(keyPath: "frame.size.width")
        widthAnimation.fromValue = fromValue
        widthAnimation.toValue = toValue
        widthAnimation.duration = 0.5

        border.addAnimation(widthAnimation, forKey: "width")
    }

    if initial {
        border.frame = layer.bounds
        border.path = UIBezierPath(rect: bounds).CGPath

        initial = false
    } else {
        movePosition()
        changesWidth()
    }
}

但是有了这个，动画完全搞砸了（最初调用了layoutSubview几次，所以它在开始时会混淆各层。

尝试在layoutSubviews中动画图层是否正确？或者我应该手动计算宽度并从那里为图层设置动画？