A definition for a smooth transition between colors, controlled by a custom function you provide, for drawing radial and axial gradient fills.


Shading means to fill using a smooth transition between colors across an area. You create a shading using a custom function with a CGFunction object. To paint with a Core Graphics shading, you call drawShading(_:). This function fills the current clipping path using the specified color gradient, calling your parametric function repeatedly as it draws.

An alternative to using a CGShading object is to use the CGGradient type. For applications that run in macOS 10.5 and later, CGGradient objects are much simpler to use. (See CGGradient.)