How do I create a circle with CALayer? - swift

Question

I have the code below tested, but when I give it constraints it becomes a little small circle:
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

Change radius and fillColor as you want. :)
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)
}
}
}

Answer 2

The rect being passed into drawRect is the area that needs to be updated, not the size of the drawing. In your case, you would probably just ignore the rect being passed in and set the circle to the size you want.
//// Oval Drawing
var ovalPath = UIBezierPath(ovalInRect: CGRectMake(0, 0, 300, 300))
UIColor.whiteColor().setFill()
ovalPath.fill()

Answer 3

The only correct way to do it:
private lazy var whiteCoin: CAShapeLayer = {
let c = CAShapeLayer()
c.path = UIBezierPath(ovalIn: bounds).cgPath
c.fillColor = UIColor.white.cgColor
layer.addSublayer(c)
return c
}()
That literally makes a layer, as you wanted.
In iOS you must correctly resize any layers you are in charge of, when the view is resized/redrawn.
How do you do that? It is the very raison d'etre of layoutSubviews.
class ProperExample: UIView {
open override func layoutSubviews() {
super.layoutSubviews()
whiteCoin.frame = bounds
}
}
It's that simple.
class ProperExample: UIView {
open override func layoutSubviews() {
super.layoutSubviews()
whiteCoin.frame = bounds
}
private lazy var whiteCoin: CAShapeLayer = {
let c = CAShapeLayer()
c.path = UIBezierPath(ovalIn: bounds).cgPath
c.fillColor = UIColor.white.cgColor
layer.addSublayer(c)
return c
}()
}