Why does the color of the drawing in my canvas change slightly when I switch between iOS to macOS targets?

Different color spaces are used in macOS and iOS by default. By default, colors on macOS use calibrated color space, while colors on iOS use the device color space by default. PaintCode renders your drawings in a way that best corresponds to the way the drawings will look on the target device. When using iOS target, the colors rendered by PaintCode correspond to the colors you see in the iOS simulator.