为什么我的CALayers不设置动画？取而代之的是，它们只是立即随新的价值而跳起来

Question

我有一个带有渐变颜色效果的CALayer。我想更改“位置”和“颜色”值以改变渐变。我正在尝试制作动画。

但是使用以下代码，它会立即更改为新值。

    let gradientDuration = 0.25

    let locationAnimation = CABasicAnimation(keyPath: "locations")
    locationAnimation.fromValue = lowerGradientView.layer.locations
    locationAnimation.toValue = newLocations

    let colorsAnimation = CABasicAnimation(keyPath: "colors")
    colorsAnimation.fromValue = lowerGradientView.layer.colors
    colorsAnimation.toValue = newColors

    let animationGroup = CAAnimationGroup()
    animationGroup.duration = gradientDuration
    animationGroup.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
    animationGroup.animations = [locationAnimation, colorsAnimation]

    lowerGradientView.layer.add(animationGroup, forKey: "locationAndColors")
    lowerGradientView.layer.locations = newLocations as [NSNumber]?
    lowerGradientView.layer.colors = newColors

我做错了什么，导致图层不使更改生效？

Answer 1

问题是这些行的末尾：

lowerGradientView.layer.locations = newLocations as [NSNumber]?
lowerGradientView.layer.colors = newColors

实际上，它们取消了动画。