为什么我的 CALayers 没有动画？相反，他们只是立即跳到位，使用新值

Question

我有一个带有渐变颜色效果的CALayer。我想更改"位置"和"颜色"值以更改渐变。我正在尝试为它制作动画。

但是使用以下代码，它只会立即更改为新值。

    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对更改进行动画处理？

Answer 1

问题是最后的这些行：

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

实际上，它们取消了动画。