From Creating iOS5 apps Develop & Design - thanks! review of enumeations

objC-enumerationreview.m

// Enumerations provide a concise, elegant method for defining a discrete set of values

typedef enum {
  SUNDAY,
  MONDAY,
  TUESDAY,
  WEDNESDAY,
  THURSDAY,
  FRIDAY,
  SATURDAY

} DAY;
const DAY HUMPDAY = WEDNESDAY;

// enum asisgns 0 to first constant, valus increase by 1
// you can also assign explicit values to 1 or more named constants

typedef enum {
  BOLD = 1;
  ITALIC = 2;
  UNDERLINE = 4;
  ALL_CAPS = 8;
  SUBSCRIPT=16;
  STRONG = BOLD;
} STYLE;