我的任务是用圆形渐变绘制线条(颜色应按圆圈变化),然后添加动画。现在我画了360层,有一定的间隔和不同的颜色。
var colours: [UIColor] = [UIColor]()
var startAngle = CGFloat(-0.5 * Double.pi)
var index = 0
func drawLayers() {
let smallAngle = (1.5 * CGFloat.pi - (-0.5 * CGFloat.pi)) / 360
if index < colours.count { //colours.count = 360
let endAngle = startAngle + smallAngle
let circlePath = UIBezierPath(arcCenter: .init(x: 100, y: 100), radius: 100, startAngle: startAngle, endAngle: endAngle, clockwise: true)
startAngle = endAngle
let shapeLayer = CAShapeLayer()
shapeLayer.path = circlePath.cgPath
shapeLayer.fillColor = UIColor.clear.cgColor
shapeLayer.strokeColor = colours[index].cgColor
shapeLayer.lineWidth = 8
view.layer.addSublayer(shapeLayer)
index += 1
Timer.scheduledTimer(
withTimeInterval: 0.004,
repeats: false) { (_) in
self.drawLayers()
}
}
}
类似的东西,但带有线性动画
谁能告诉我怎样做才是正确的?
iOS 现在内置了圆形(圆锥形)渐变。所以我只需要一次渐变,然后为用作蒙版的单个路径设置动画。这只是两层,工作量少得多,真正的动画和真正的渐变。
Example:
这是我的测试代码;根据需要更改颜色和数字:
let grad = CAGradientLayer()
grad.type = .conic
grad.colors = [UIColor.red.cgColor, UIColor.green.cgColor, UIColor.red.cgColor]
grad.startPoint = CGPoint(x: 0.5, y: 0.5)
grad.frame = CGRect(x: 100, y: 100, width: 200, height: 200)
self.view.layer.addSublayer(grad)
let c = CAShapeLayer()
let p = UIBezierPath(ovalIn: CGRect(x: 20, y: 20, width: 160, height: 160))
c.path = p.cgPath
c.fillColor = UIColor.clear.cgColor
c.strokeColor = UIColor.black.cgColor
c.lineWidth = 8
grad.mask = c
c.strokeEnd = 0
要使动画发生,只需说:
c.strokeEnd = 1
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