Ios 将动画重新应用到现有层

以下代码用于根据保存的数据绘制动画图表。图表路径从其初始行变形为数据库形状。这一切都是一种魅力

但是，当我从另一个视图控制器输入新数据并返回时 我想重新激活变形（现在从上一个最终形状到新形状）。数据被加载，最终的形状是它应该的。however路径和渐变动画从不设置动画。它只是瞬间处于它的最终位置

事务完成块确实在运行，因此我似乎无法找出问题所在

非常感谢

  func fromToAnimPath(fromPath:CGMutablePath,toPath:CGMutablePath)->CAShapeLayer{

    var graphShape:CAShapeLayer!
    if statisticHolderView.layer.sublayers?.count == 2{
        if let oldShape = statisticHolderView.layer.sublayers?.last{
            print("reusing ols cashapelayer from statistichlderview")
            graphShape = oldShape as! CAShapeLayer

        }

    }else{

        print("creating layer for the first time")
        graphShape = CAShapeLayer()
        graphShape.fillColor = nil
        graphShape.strokeColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1).cgColor
        graphShape.lineWidth = 2
        graphShape.path = fromPath
    }
    let gradiantAnim = CABasicAnimation.init(keyPath: "locations")
    gradiantAnim.fromValue = [1,1,1]
    gradiantAnim.toValue = [0.0,0.2,1]
    gradiantAnim.duration = 0.5
    gradiantAnim.timingFunction = CAMediaTimingFunction.init(name: kCAMediaTimingFunctionEaseOut)

    let maskLayer = CAShapeLayer()
    var gradiant:CAGradientLayer!

    if  ((graphShape.sublayers?.count) != nil) {

        if let oldMask = graphShape.sublayers?.first{
            gradiant = oldMask as! CAGradientLayer
            print("Reusing gradiant")
        }
    }else{
        gradiant = CAGradientLayer()
        gradiant.startPoint = CGPoint.init(x: 0, y: 1)
        gradiant.endPoint = CGPoint.init(x: 0, y: 0)
        gradiant.colors = [#colorLiteral(red: 1, green: 1, blue: 1, alpha: 0).cgColor,#colorLiteral(red: 1, green: 1, blue: 1, alpha: 0).cgColor,#colorLiteral(red: 1, green: 1, blue: 1, alpha: 0.9).cgColor]
        gradiant.locations=[0,0.2,1]
        gradiant.backgroundColor = nil
        gradiant.opacity = 0
    }

    maskLayer.frame = toPath.boundingBox
    maskLayer.path = toPath
    gradiant.frame = maskLayer.bounds
    gradiant.mask = maskLayer

    CATransaction.begin()
    CATransaction.setCompletionBlock {
        gradiant.opacity = 1
        gradiant.add(gradiantAnim, forKey: nil)

    }

    let graphAnim = CABasicAnimation.init(keyPath: "path")
    graphAnim.fromValue = graphShape.path
    graphShape.path = toPath
    graphAnim.toValue = graphShape.path
    graphAnim.timingFunction = CAMediaTimingFunction.init(name: kCAMediaTimingFunctionEaseOut)
    graphAnim.duration = 2.7

    graphShape.add(graphAnim, forKey: nil)

    if !didDrawInitialStartGraph{
        print("inserted the graiant as a sublayer")
        graphShape.insertSublayer(gradiant, at: 0)
    }

    CATransaction.commit()

    pathCurve.addPath(toPath)
    didDrawInitialStartGraph = true

    return graphShape
}

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进一步检查，可能是因为完成块将在不考虑动画持续时间的情况下瞬时运行，所以在所有第二次添加动画。进一步检查，可能是因为完成块将在不考虑动画持续时间的情况下瞬时运行，所以在所有第二次添加动画期间