How to draw rectangles on a image in swift - ios

Question

Hello I'm trying to draw some rectangles on a UIImageView but when I add the background image the rectangle drawing is not working anymore:
This is the code:
import UIKit
class DrawView: UIView {
var startPos: CGPoint?
var endPos: CGPoint?
override func draw(_ rect: CGRect) {
guard let context = UIGraphicsGetCurrentContext() else {
return
}
if startPos != nil && endPos != nil {
print("both there")
drawRectangle(context: context, startPoint: startPos!, endPoint: endPos!, isFilled: false)
}
}
public func drawRectangle(context: CGContext, startPoint: CGPoint, endPoint: CGPoint, isFilled: Bool) {
let xx = startPoint
let xy = CGPoint(x:endPoint.x, y:startPoint.y)
let yx = CGPoint(x:startPoint.x, y:endPoint.y)
let yy = endPoint
print("draw rectangle")
context.move(to: xx)
context.addLine(to: xx)
context.addLine(to: xy)
context.addLine(to: yy)
context.addLine(to: yx)
context.addLine(to: xx)
context.setLineCap(.square)
context.setLineWidth(8)
if isFilled {
context.setFillColor(UIColor.purple.cgColor)
context.fillPath()
} else {
context.setStrokeColor(UIColor.red.cgColor)
context.strokePath()
}
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let position = touch.location(in: self)
print(position)
startPos = position
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let position = touch.location(in: self)
print(position)
endPos = position
setNeedsDisplay()
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let position = touch.location(in: self)
print(position)
endPos = position
setNeedsDisplay()
}
}
func addBackground() {
// screen width and height:
let width = UIScreen.main.bounds.size.width
let height = UIScreen.main.bounds.size.height
let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: width, height: height))
imageView.image = UIImage(named: "img1.jpg")
// you can change the content mode:
imageView.contentMode = UIView.ContentMode.scaleAspectFill
self.addSubview(imageView)
self.sendSubviewToBack(imageView)
}
}
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var drawView: DrawView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
drawView.addBackground()
}
}
Im suspecting that I'm not using the correct UIGraphicsGetCurrentContext after setting the image but I was not able to figure it out how to fix it.