Animate UIBezierPaths-不工作-Swift

Question

我正在尝试创建一个一起动画的箭头。但是，有两个问题：

1.线条没有动画，整个箭头只是出现在屏幕上

2.箭头填充为黑色，而不仅仅是轮廓（我的目标是）

let shapeLayer = CAShapeLayer()
let bezierPath = UIBezierPath()

//set up lines
bezierPath.move(to: CGPoint(x: 50.5, y: 158.5))
bezierPath.addLine(to: CGPoint(x: 221.5, y: 158.5))
bezierPath.addLine(to: CGPoint(x: 171.5, y: 108.5))
bezierPath.addLine(to: CGPoint(x: 197.5, y: 82.5))
bezierPath.addLine(to: CGPoint(x: 292.5, y: 177.5))
bezierPath.addLine(to: CGPoint(x: 197.5, y: 272.5))
bezierPath.addLine(to: CGPoint(x: 171.5, y: 246.5))
bezierPath.addLine(to: CGPoint(x: 221.5, y: 196.5))
bezierPath.addLine(to: CGPoint(x: 50.5, y: 196.5))
bezierPath.addLine(to: CGPoint(x: 50.5, y: 158.5))
UIColor.black.setStroke()
bezierPath.lineWidth = 1
bezierPath.stroke()
shapeLayer.path = bezierPath.cgPath

// set up animation
let animation2 = CABasicAnimation(keyPath: "strokeEnd")

animation2.fromValue = 0.0
animation2.toValue = 1.0
animation2.duration = 2.5
shapeLayer.add(animation2, forKey: "drawLineAnimation")

eeView.layer.addSublayer(shapeLayer)

如果有人能帮助我解决这些问题，那就太棒了。任何帮助将不胜感激！预先非常感谢。

干杯，西奥

Answer 1

问题是这个序列：

shapeLayer.add(animation2, forKey: "drawLineAnimation")
eeView.layer.addSublayer(shapeLayer)

您不能将动画添加到图层，然后将该图层添加到界面。您只能将动画添加到界面中已有的图层中。

另外，您还需要设置形状图层的fillColor和strokeColor。

这是实际的代码。在某个地方，你会这样说：

    let shapeLayer = CAShapeLayer()
    shapeLayer.fillColor = UIColor.clear.cgColor
    shapeLayer.strokeColor = UIColor.black.cgColor
    eeView.layer.addSublayer(shapeLayer)
    self.shape = shapeLayer // self.shape is a property

然后，过一段时间，你会说：

    let shapeLayer = self.shape!
    let bezierPath = UIBezierPath()
    // ... rest of your code goes here: create path, add path to shape layer ...
    // ... create animation, add animation to shape layer