Cocoa in a Nutshell

Working with Color

Colors in the Application Kit are represented by instances of the NSColor class, which provides an interface for creating colors and setting the color used by the current graphics context. AppKit supports several color spaces that fall into three categories:

Device-dependent

Color spaces support colors that may appear differently on different devices (such as a color printer or monitor).

Device-independent

Colors are calibrated so they appear the same on any output device.

Named

Color spaces represent colors that don’t correspond to numerical values, but are referenced in a catalogue of named colors.

The six color spaces supported by the Application Kit are based on these three categories, as detailed in Table 4-3.

Table 4-3. Color spaces supported by the Application Kit

Color space name	Description
NSDeviceCMYKColorSpace	Cyan, magenta, yellow, black, and alpha components
NSDeviceRGBColorSpace	Red, green, blue, and alpha components; or hue, saturation, brightness, and alpha components
NSCalibratedRGBColorSpace	Red, green, blue, and alpha components; or hue, saturation, brightness, and alpha components
NSDeviceWhiteColorSpace	White and alpha components (grayscale)
NSCalibratedWhiteColorSpace	White and alpha components (grayscale)
NSNamedColorSpace	Catalog name and color name components

The color spaces that are NSDevice... are device-dependent color spaces, while those that are NSCalibrated... color spaces are device-independent. Table 4-3 lists constant ...