Draw lines with touch - ios

Question

I am new to swift and I have no experience handling core graphics.
I need to develop an application in ios swift to draw graphs. Here graph refers to graph theory. I need to draw the nodes by tapping on the screen and draw lines between two nodes when they are selected. So far I can only draw circles, but I need that when touching two points a line appears between the two. And I need that if I already draw a circle, when they tap again they can move. How can I draw the lines?
I will appreciate any support
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor.lightGray
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
// Set the Center of the Circle
// 1
let circleCenter = touch.location(in: view)
// Set a random Circle Radius
// 2
let circleWidth = CGFloat(25.7) //+ (arc4random() % 50))
let circleHeight = circleWidth
// Create a new CircleView
// 3
let circleView = CircleView(frame: CGRect(x: circleCenter.x, y: circleCenter.y, width: circleWidth, height: circleHeight))
view.addSubview(circleView)
}
}
}
Class CircleView.swift
class CircleView: UIView {
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.clear
}
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func draw(_ rect: CGRect) {
// Get the Graphics Context
if let context = UIGraphicsGetCurrentContext() {
// Set the circle outerline-width
context.setLineWidth(5.0);
// Set the circle outerline-colour
UIColor.red.set()
// Create Circle
let center = CGPoint(x: frame.size.width/2, y: frame.size.height/2)
let radius = (frame.size.width - 10)/2
context.addArc(center: center, radius: radius, startAngle: 0.0, endAngle: .pi * 2.0, clockwise: true)
// Draw
context.strokePath()
}
}
}