Draw UIBezierPath outside of UIView::drawRect()?

Question

I'm trying to draw a set of small circles around the edge of a view to mirror physical lights (pixels) I'm controlling in my app. These circles will change color frequently. So I've created a PixelSimulator object to draw each circle into a custom UIView object.

Here's the relevant code

class PixelSimulator {
  let size: CGSize;
  let color: UIColor;
  let pixelPath: UIBezierPath;

  init (point: CGPoint, size: CGSize, pixel: Pixel) {
    self.point = point;
    self.size = size;
    self.pixel = pixel;

    pixelRect = CGRect(origin: point, size: size);
    pixelPath = UIBezierPath(ovalInRect: pixelRect);

    color = pixel.color;
  }

  func render () {
    UIGraphicsBeginImageContext(size);

    color.setFill();
    pixelPath.fill();

    UIGraphicsEndImageContext();
  }
}

I've tried a different approach using CGContextAddEllipseInRect(context, pixelRect) to no avail. I've also tried declaring the pixelPath inside of the render() method, also to no avail.

What do I need to change to get my bezierPath drawn onto the screen at any time, inside of drawRect() or out of it?

Answer 1

I'd remove the image context and just directly draw. I'd call render only from inside draw rect.

When the colour changes I'd update the appropriate simulators and post a notification to let the 'system' know that it happened. In this case a notification is appropriate because you don't want to know what is interested about the change event and multiple things in the system may be interested.

When the notification is received by your view controller it simply calls setNeedsDisplay on the view which will result in the simulators being rendered on the next draw cycle.