Reposition CGPath/UIBezierPath in View

Question

Is it possible to reposition an already drawn CGPath/UIBezierPath on a view? I would like to move or change a path\'s position then perhaps recall the drawinRect method to just

Answer 1

I did it a bit different from other answers above.

Let's suppose you want to move a circle, first I define its center coordinates and radius in global variables, like this:

var center: CGPoint = CGPoint(x: UIScreen.main.bounds.width/2, y: UIScreen.main.bounds.height/2)
var radius: CGFloat = 10

I draw this circle like in the code bellow:

override func draw(_ rect: CGRect) {
    super.draw(rect)  
    drawCircle()
}

func drawCircle() {
    let circle = UIBezierPath(
        arcCenter: self.center,
        radius: CGFloat(self.radius),
        startAngle: CGFloat(0),
        endAngle: CGFloat(2*Double.pi),
        clockwise: true)

    let circleLayer = CAShapeLayer()
        circleLayer.path = circle.cgPath
        circleLayer.fillColor = UIColor.clear.cgColor
        circleLayer.strokeColor = UIColor.black.cgColor
        circleLayer.lineWidth = 10.0
        layer.addSublayer(circleLayer)
}

Inside the UIView, I have a touchesMoved(), like this:

override func touchesMoved(_ touches: Set, with event: UIEvent?){
    if let touch = touches.first {
        let pos = touch.location(in: self)

        if (pow(pos.x-self.center.x,2) + pow(pos.y-self.center.y,2) <= pow(self.radius,2)){
                self.center = CGPoint(x: pos.x, y: pos.y)
        }

        setNeedsDisplay()
    }
}

Everytime the touch is inside the circle, its center coordinates are updated and the UIView is redrawn with setNeedDisplay(), so the circle moves.

Hope it helps someone!