How to create a elliptical CGPathRef?

Question

I am new to core graphic in cocoa. I have a picture of a egg and I am using Sprite kit to simulation physics of free falling of an egg. I need to set the egg's physicsBody property. How to create an elliptical CGPathRef for the purpose?

For an egg shape path, I have to create an half of circle with half of oval. How to do it?

Answer 1

Allow me to point you to the reference documentation of CGPath, where you will find CGPathCreateWithEllipseInRect.

Answer 2

Actually, I just ran into this problem in an app that I was writing to create some graphics assets.

CGPathMoveToPoint(path, nil, 10, 95);
CGPathAddLineToPoint(path, nil, (5 + SIZE) * 1.5, 95 - SIZE * 1 / 3);

CGAffineTransform t = CGAffineTransformMakeScale(1.5, 1.0);
CGPathAddArc(path, &t, SIZE + 5, 95 - SIZE * 4 / 3, SIZE, M_PI / 2, -M_PI * 5 / 4, YES);
CGPathCloseSubpath(path);

TL;DR

You have to use CGAffineTransform in order to get an arc of an ellipse.