UIBezierPath Star with rounded corners

Question

I have created a star shape image by UIBezierPath using this code:

    let path = UIBezierPath()
    let center = CGPoint(x: rect.width / 2.0, y: rect.height / 2.0)
    let xCenter: CGFloat = center.x
    let yCenter: CGFloat = center.y
    let w = rect.width
    let r = w / 2.0
    let flip: CGFloat = -1.0 // use this to flip the figure 1.0 or -1.0
    let polySide = CGFloat(5)
    let theta = 2.0 * Double.pi * Double(2.0 / polySide)
    path.move(to: CGPoint(x: xCenter, y: r * flip + yCenter))
    for i in 1..<Int(polySide) {
        let x: CGFloat = r * CGFloat( sin(Double(i) * theta) )
        let y: CGFloat = r * CGFloat( cos(Double(i) * theta) )
        path.addLine(to: CGPoint(x: x + xCenter, y: y * flip + yCenter))
    }
    path.close()

And I want to give corner radius to each corner of the star. I tried smth but I could not figure it out. Can you help me to do this?

Answer 1

Here is a custom UIView that computes a path for a 5-point star with a cornerRadius:

class RoundedStar : UIView {
    var cornerRadius: CGFloat = 10 { didSet { setNeedsDisplay() } }
    var rotation: CGFloat = 54     { didSet { setNeedsDisplay() } }
    var fillColor = UIColor.red    { didSet { setNeedsDisplay() } }

    override func draw(_ rect: CGRect) {
        let path = UIBezierPath()
        let center = CGPoint(x: rect.width / 2, y: rect.height / 2)
        let r = rect.width / 2
        let rc = cornerRadius
        let rn = r * 0.95 - rc

        var cangle = rotation
        for i in 1 ... 5 {
            // compute center point of tip arc
            let cc = CGPoint(x: center.x + rn * cos(cangle * .pi / 180), y: center.y + rn * sin(cangle * .pi / 180))

            // compute tangent point along tip arc
            let p = CGPoint(x: cc.x + rc * cos((cangle - 72) * .pi / 180), y: cc.y + rc * sin((cangle - 72) * .pi / 180))

            if i == 1 {
                path.move(to: p)
            } else {
                path.addLine(to: p)
            }

            // add 144 degree arc to draw the corner
            path.addArc(withCenter: cc, radius: rc, startAngle: (cangle - 72) * .pi / 180, endAngle: (cangle + 72) * .pi / 180, clockwise: true)

            cangle += 144
        }

        path.close()
        fillColor.setFill()
        path.fill()
    }
}

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Example run in the Playground:

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Simulator Demo

Code:

class ViewController: UIViewController {

    @IBOutlet weak var rstar: RoundedStar!
    @IBOutlet weak var cornerRadiusLabel: UILabel!
    @IBOutlet weak var rotationlabel: UILabel!

    @IBAction func cornerRadiusChanged(_ sender: UISlider) {
        rstar.cornerRadius = CGFloat(sender.value)
        cornerRadiusLabel.text = "Corner Radius: \(Int(sender.value))"
    }

    @IBAction func rotationChanged(_ sender: UISlider) {
        rstar.rotation = CGFloat(sender.value)
        rotationlabel.text = "Rotation: \(Int(sender.value))"
    }
}