我如何使用 CALayer 创建一个圆圈？

Question

我测试了下面的代码，但是当我给它约束时它变成了一个小圆圈：

 override func drawRect(rect: CGRect) {
var path = UIBezierPath(ovalInRect: rect)
fillColor.setFill()
path.fill()

//set up the width and height variables
//for the horizontal stroke
let plusHeight:CGFloat = 300.0
let plusWidth:CGFloat = 450.0

//create the path
var plusPath = UIBezierPath()

//set the path's line width to the height of the stroke
plusPath.lineWidth = plusHeight

//move the initial point of the path
//to the start of the horizontal stroke
plusPath.moveToPoint(CGPoint(
  x:self.bounds.width/2 - plusWidth/2 + 0.5,
  y:self.bounds.height/2 + 0.5))

//add a point to the path at the end of the stroke
plusPath.addLineToPoint(CGPoint(
  x:self.bounds.width/2 + plusWidth/2 + 0.5,
  y:self.bounds.height/2 + 0.5))

}

Answer 1

传入drawRect的rect是需要更新的区域，不是绘图的大小。在您的情况下，您可能会忽略传入的矩形并将圆圈设置为您想要的大小。

    //// Oval Drawing
    var ovalPath = UIBezierPath(ovalInRect: CGRectMake(0, 0, 300, 300))
    UIColor.whiteColor().setFill()
    ovalPath.fill()

Answer 2

根据需要更改半径和填充颜色。 :)

import Foundation
import UIKit

class CircleLayerView: UIView {
    var circleLayer: CAShapeLayer!

    override func draw(_ rect: CGRect) {
        super.draw(rect)
        if circleLayer == nil {
            circleLayer = CAShapeLayer()
            let radius: CGFloat = 150.0
            circleLayer.path = UIBezierPath(roundedRect: CGRect(x: 0, y: 0, width: 2.0 * radius, height: 2.0 * radius), cornerRadius: radius).cgPath
            circleLayer.position = CGPoint(x: self.frame.midX - radius, y: self.frame.midY - radius)
            circleLayer.fillColor = UIColor.blue.cgColor
            self.layer.addSublayer(circleLayer)
        }
    }
}

我如何使用 CALayer 创建一个圆圈？

How do I create a circle with CALayer?

calayer

swift