宣告一個類方法

Header file UIColor+XYZPalette.h:

@interface UIColor (XYZPalette)

+(UIColor *)xyz_indigoColor;

@end

和實施 UIColor+XYZPalette.m：

@implementation UIColor (XYZPalette)

+(UIColor *)xyz_indigoColor
{
    return [UIColor colorWithRed:75/255.0f green:0/255.0f blue:130/255.0f alpha:1.0f];
}

@end