How to draw a color wheel in objective-c

Question

I am trying to draw a color wheel for an iPhone, but I can\'t get the gradient to rotate around a point. I am trying to use gradients but objective-c provides a linear grad

Answer 1

It's now possible to draw a color wheel image using CIFilter (as of iOS 10). More info in this blog post (the code is Swift but can be translated directly to Objective-C)