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我正在将此库从 objc 移植到 Swift，但我无法找出复制器层 instanceCount 未对动画执行任何操作的原因。有什么想法吗？
如果您查看库，它有多个图层实例同时动画，但在我的代码中，一次只有一个图层动画。
https://github.com/shu223/PulsingHalo/blob/master/PulsingHalo/PulsingHaloLayer.m
public class PulsingHaloLayer2: CAReplicatorLayer {
var fromValueForRadius: Float = 0.0
var fromValueForAlpha: Float = 0.45
var keyTimeForHalfOpacity: Float = 0.2
var animationDuration: NSTimeInterval = 3.0
var pulseInterval: NSTimeInterval = 0.0
var useTimingFunction: Bool = true
let animationGroup: CAAnimationGroup = CAAnimationGroup()
var repetitions: Float = Float.infinity
var radius: CGFloat = 200.0 {
didSet {
let tempPos = position
let diameter = radius * 2
bounds = CGRect(x: 0.0, y: 0.0, width: diameter, height: diameter)
cornerRadius = radius
position = tempPos
}
}
var haloLayerNumber: Int = 4 {
didSet {
instanceCount = 4
instanceDelay = (animationDuration + pulseInterval) / Double(haloLayerNumber)
}
}
override init() {
super.init()
contentsScale = UIScreen.mainScreen().scale
opacity = 0.0
backgroundColor = UIColor.blueColor().CGColor
haloLayerNumber = 4
setupAnimationGroup()
addAnimation(animationGroup, forKey: "pulse")
}
required public init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupAnimationGroup() {
animationGroup.duration = animationDuration + pulseInterval
animationGroup.repeatCount = repetitions
animationGroup.removedOnCompletion = false
if useTimingFunction {
let defaultCurve = CAMediaTimingFunction(name: kCAMediaTimingFunctionDefault)
animationGroup.timingFunction = defaultCurve
}
let opacityAnimation = CAKeyframeAnimation(keyPath: "opacity")
opacityAnimation.duration = animationDuration
opacityAnimation.values = [fromValueForAlpha, 0.45, 0]
opacityAnimation.keyTimes = [0, keyTimeForHalfOpacity, 1]
let scaleAnimation = CABasicAnimation(keyPath: "transform.scale.xy")
scaleAnimation.fromValue = fromValueForRadius
scaleAnimation.toValue = 1
scaleAnimation.duration = animationDuration
animationGroup.animations = [opacityAnimation, scaleAnimation]
}
}