Large number of bitwise enums - objective-c

Question

I've got a question regarding bitwise enums that I just can't seem to resolve. I've got a number of flags that are represented by a bitwise enum as in the following example:
enum
{
EnumNone=0,
EnumOne = 1<<0,
EnumTwo = 1<<1,
EnumThree = 1<<2,
EnumFour = 1<<3
};
typedef NSUInteger MyEnum;
All is fine with the above example. Based on my research and various helpful posts in stackoverflow (this for example), I've concluded that, using the above example, I'm essentially given 32 options (or shifts if you will), each option representing 1 bit in a 32-bit series of options, which basically tells me that I can go all the way to EnumThirtyTwo = 1 << 31.
My question is this:
Suppose I've more than 32, say 75 flags for example, to represent using a bitwise enum. How would that best be represented?
enum
{
EnumNone=0,
EnumOne = 1<<0,
EnumTwo = 1<<1,
EnumThree = 1<<2,
EnumFour = 1<<3,
...
...
EnumSeventyFive = 1<<75
};
typedef NSUInteger MyEnum;
Would it be a simple matter of changing the declaration of my enum type, say, to: typedef long int MyEnum; or typedef long MyEnum?

Answer 1

You can use a few simple macros/functions and a struct containing a char array of sufficient size - gives you call-by-value semantics, i.e. just like real enums. E.g. something along the lines of (typed directly into answer):
typedef struct
{
char bits[10]; // enough for 80 bits...
} SeventyFiveFlags;
typedef enum
{
EnumOne = 0,
...
EnumSeventyFive = 74
} SeventyFiveFlagNames;
NS_INLINE BOOL testFlag(SeventyFiveFlags flags, SeventyFiveFlagNames bit)
{
return (flags.bits[bit >> 3] & (1 << (bit & 0x7))) != 0;
}
However you can also use the bitstring(3) functions/macros if you are OK with call-by-reference semantics. These create (heap or stack) bit strings of any length. Use your enum to provide symbolic names for the bit numbers rather than masks, e.g.:
#include <bitstring.h>
typedef enum
{
EnumOne = 0,
...
EnumSeventyFive = 74,
SeventyFiveFlagsSize = 75
} SeventyFiveFlagNames;
typedef bitstr_t *SeventyFiveFlags;
// local (stack) declaration & use
SeventyFiveFlags seventyFive;
bit_decl(seventyFive, SeventyFiveFlagsSize); // declare
bit_nclear(seventyFive, EnumOne, EnumSeventyFive); // set all false
if( bit_test(seventyFive, EnumFortyTwo) ) // test
You can always wrap this up as a class if heap allocation only is OK.

Answer 2

Maybe I am talking about something irrelevant.
I think having too much flag in an enum is not a good practise. Having this large amount of flag, there must be ways to group them up like:
enum
{
EnumNone=0,
EnumOne = 1<<0,
EnumTwo = 1<<1,
EnumThree = 1<<2,
EnumFour = 1<<3
};
typedef NSUInteger widthRelated;
enum
{
EnumNone=0,
EnumOne = 1<<0,
EnumTwo = 1<<1,
EnumThree = 1<<2,
EnumFour = 1<<3
};
typedef NSUInteger heightRelated;