Drawing differences of 2 UIBezierPath

Question

I want to draw differences between 2 UIBezierPath (see screenshot) in order to draw only rounded corners as you can see on my screenshot (figure C)

Here is my code:

let context = UIGraphicsGetCurrentContext()
CGContextSaveGState(context)

let rectanglePath = UIBezierPath(rect: rect)
CGContextAddPath(context, rectanglePath.CGPath)
CGContextEOClip(context)

let roundedRectanglePath = UIBezierPath(roundedRect: productRect, byRoundingCorners: roundedCorners, cornerRadii: CGSize(width: 6, height: 6))
CGContextAddPath(context, roundedRectanglePath.CGPath)
CGContextFillPath(context)

CGContextRestoreGState(context)

Unfortunately it doesn't work. I only draw rounded black rectangle.

Do you have an idea?

Thanks a lot.

Answer 1

You can use one path:

let path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius)
path.append(UIBezierPath(rect: bounds))
path.usesEvenOddFillRule = true

UIColor.black.setFill()
path.fill()

Or you can use CoreGraphics:

let path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius)
path.append(UIBezierPath(rect: bounds))

let context = UIGraphicsGetCurrentContext()!
context.addPath(path.cgPath)
context.setFillColor(UIColor.black.cgColor)
context.fillPath(using: .evenOdd)

That yields:

See previous revision of this answer for Swift 2 rendition.