To define a category bit mask enum in Objective-C I used to type:
typedef NS_OPTIONS(NSUInteger, CollisionCategory)
CollisionCategoryPlayerSpaceship = 0,
CollisionCategoryEnemySpaceship = 1 << 0,
CollisionCategoryChickenSpaceship = 1 << 1,
What you could do is use the binary literals:
However, in Swift you cannot bitwise-OR enums, so there is really no point in using bitmasks in enums. Check out this question for a replacement for NS_OPTION.