// paint curve for sun
    let path = UIBezierPath()

    let imageSunName = "small_sun.png"
    let imageSun = UIImage(named: imageSunName)
    let imageView = UIImageView(image: imageSun!)

    imageView.frame = CGRect(x: xStart,y: yStart,width: 24,height: 24)
    self.view.addSubview(imageView)

    path.moveToPoint(CGPoint(x: xStart,y: yStart))

    path.addQuadCurveToPoint(CGPoint(x: xEnd,y: yEnd),controlPoint: CGPoint(x: xMiddleTop,y: yMiddleTop))

    let animation = CAKeyframeAnimation(keyPath: "position")
    animation.path = path.CGPath

    animation.repeatCount = 0
    animation.duration = 5.0

    imageView.layer.addAnimation(animation,forKey: "animate position along path")

尽管如此,还有两个问题：

>我想仅沿路径部分移动图像(根据当前时间对日出/日落) – 如何做到这一点？
>动画停止后图像跳转到原点位置 – 我该怎样避免这种情况？

干杯