draw only one object by button and undo button

Question

i am beginner in swift, and now i am a little fighting with maybe simple thing.

if i click on button undo, the MyDrawView should be clear, and if i click on polygon a fill for example purple, and then i click on circle, to have only one object.

something like this:

but now i have this:

my code:

import UIKit
import QuartzCore

class MyDrawView: UIView{

    var circle = UIBezierPath()
    let polygon = UIBezierPath()

    let shapeLayer1 = CAShapeLayer()
    let shapeLayer2 = CAShapeLayer()


    func drawCircle(){
        circle = UIBezierPath(arcCenter: CGPoint(x: 200, y: 300), radius: CGFloat(100), startAngle: CGFloat(0), endAngle: CGFloat(Double.pi * 2), clockwise: true)

        shapeLayer1.path = circle.cgPath

        shapeLayer1.fillColor = UIColor.clear.cgColor
        shapeLayer1.strokeColor = UIColor.black.cgColor 
        shapeLayer1.lineWidth = 3.0 

        layer.addSublayer(shapeLayer1)
    }


    func drawPolygon(){
        polygon.move(to: CGPoint(x: 50, y: 50))
        polygon.addLine(to: CGPoint(x: 230, y: 90))
        polygon.addLine(to: CGPoint(x: 240, y: 250))
        polygon.addLine(to: CGPoint(x: 50, y: 280))
        polygon.addLine(to: CGPoint(x: 100, y: 150))
        polygon.addLine(to: CGPoint(x: 50, y: 50))

        shapeLayer4.path = polygon.cgPath

        shapeLayer2.fillColor = UIColor.clear.cgColor 
        shapeLayer2.strokeColor = UIColor.black.cgColor 
        shapeLayer2.lineWidth = 3.0 

         layer.addSublayer(shapeLayer2)
    }


    @IBAction func clickButtonUndo(_ sender: UIButton) {

    }

    @IBAction func clickButtonCircle(_ sender: UIButton) {
        drawCircle()
    }

    @IBAction func clickButtonPolygon(_ sender: UIButton) {
        drawPolygon()
    }




    @IBAction func buttonPurple(_ sender: UIButton) {
        shapeLayer1.path = circle.cgPath
        shapeLayer2.path = polygon.cgPath

        shapeLayer1.fillColor = UIColor.purple.cgColor
        shapeLayer1.strokeColor = UIColor.black.cgColor 
        shapeLayer1.lineWidth = 3.0 

        shapeLayer2.fillColor = UIColor.purple.cgColor 
        shapeLayer2.strokeColor = UIColor.black.cgColor
        shapeLayer2.lineWidth = 3.0 

        layer.addSublayer(shapeLayer1)
        layer.addSublayer(shapeLayer2)

    }

}

Answer 1

you can make an algorithm with true/false for example:

var circleBool = true

var polygonBool = true

@IBAction func clickButtonCircle(_ sender: UIButton) {
  if circleBool == true {
    drawCircle()
  polygonBool = false

} }

@IBAction func clickButtonPolygon(_ sender: UIButton) {
   if polygonBool == true {
    drawPolygon()
   circleBool = false

}

@IBAction func clickButtonUndo(_ sender: UIButton) {
circleBool = true
polygonBool = true

}

(for undo button idk how to clear but try to draw x:0 and y:0)