通过CGPath绘制出空心的圆形
func drawCircular() {
let centerX = view.bounds.size.width/2
let boundingRect = CGRect(x:centerX-100, y:50, width:200, height:200)
var orbitPath: CGPath!
//通过CGPath的ellipseIn方法,创建一个圆形的CGPath
orbitPath = CGPath(ellipseIn: boundingRect, transform: nil)
//绘制路线的图层
drawPath(path: orbitPath)
}
///绘制路线的图层
func drawPath(path: CGPath) {
let pathLayer = CAShapeLayer()
pathLayer.frame = self.view.bounds
pathLayer.path = path
pathLayer.fillColor = nil
pathLayer.lineWidth = 3
pathLayer.strokeColor = UIColor.white.cgColor
self.view.layer.addSublayer(pathLayer)
}