Swift : drawing the dots in loop - ios

Question

I am trying to draw multiple dots in a loop by passing set of points. But not a single dot is getting drawn on view. Idea - I am parsing xml document and extracting point to draw it on view.
Edit - I have updated the code with suggested changes and it is working.
//View Class
class DrawTrace: UIView
{
var points = [CGPoint]()
{
didSet {
setNeedsDisplay()
}
}
override func draw(_ rect: CGRect)
{
let size = CGSize(width: 1, height: 1)
UIColor.white.set()
for point in points
{
print(point.x,point.y)
let dot = UIBezierPath(ovalIn: CGRect(origin: point, size: size))
dot.fill()
}
}
}
//View Controller Class
class ViewController: UIViewController
{
var object : traceDoc = traceDoc()
let trace = DrawTrace(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
override func viewDidLoad()
{
super.viewDidLoad()
object.collectionOfData()
trace.points = object.tracePoints
self.view.addSubview(trace)
}
}
Added view instance to view hierarchy that is in view controller.Created instance of DrawTrace and appended to tracepoints array.

Answer 1

Your code is way more complex than it needs to be. One big issue is that you keep adding more and more layers each time draw is called.
There is no need to use layers to draw dots in your custom view. Here is a much simpler solution:
class DrawTrace: UIView
{
var points = [CGPoint]() {
didSet {
setNeedsDisplay()
}
}
override func draw(_ rect: CGRect)
{
let size = CGSize(width: 2, height: 2)
UIColor.black.set()
for point in points {
let dot = UIBezierPath(ovalIn: CGRect(origin: point, size: size))
// this just draws the circle by filling it.
// Update any properties of the path as needed.
// Use dot.stroke() if you need an outline around the circle.
dot.fill()
}
}
}
let trace = DrawTrace(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
trace.backgroundColor = .white
trace.points = [ CGPoint(x: 10, y: 10), CGPoint(x: 35, y: 100)]
The above can be copied into a playground.

Answer 2

Black dotes on black view aren't visible, try to make dotes white:
shapeLayer.fillColor = UIColor.white.cgColor
shapeLayer.strokeColor = UIColor.white.cgColor
Also, in UIViewController code you are not adding your DrawTrace to views hierarchy, try in viewDidLoad:
self.view.addSubview(drawTraceInstance)
Finally, it seems that you have to iterate over array of CGPoint's. Instead of use stride, user FastEnumeration over Array:
for point in points
{
drawDot(x: point.x, y: point.y,Color: fillColor, size: size)
}