Objective-C Enum-TO-NSString and Vice versa.

HZClassUsingEnum.h

// Declare enums like so:
#define IMAGE_STATUS(XX)  \
XX(kDOImageStatusOK, = 0) \
XX(kDOImageStatusCached, )\
XX(kDOImageStatusRetry, ) 
DECLARE_ENUM(DOImageStatus, IMAGE_STATUS)

HZClassUsingEnum.m

// Define Enum-To-NSString functions like so:
DEFINE_ENUM(DOImageStatus, IMAGE_STATUS)

// use them like this:
NSString *imageStatus = NSStringFromDOImageStatus(kDOImageStatusOK);
DOImageStatus statusFromString = DOImageStatusFromNSString(@"kDOImageStatusCached");

Macros.h

//
// Based on http://stackoverflow.com/a/202511
//

#pragma mark - Enum Factory Macros
// expansion macro for enum value definition
#define ENUM_VALUE(name,assign) name assign,

// expansion macro for enum to string conversion
#define ENUM_CASE(name,assign) case name: return @#name;

// expansion macro for string to enum conversion
#define ENUM_STRCMP(name,assign) if (![string isEqualToString:@#name]) return name;

/// declare the access function and define enum values
#define DECLARE_ENUM(EnumType,ENUM_DEF) \
typedef enum EnumType { \
ENUM_DEF(ENUM_VALUE) \
}EnumType; \
NSString *NSStringFrom##EnumType(EnumType value); \
EnumType EnumType##FromNSString(NSString *string); \

// Define Functions
#define DEFINE_ENUM(EnumType, ENUM_DEF) \
NSString *NSStringFrom##EnumType(EnumType value) \
{ \
switch(value) \
{ \
ENUM_DEF(ENUM_CASE) \
default: return @""; \
} \
} \
EnumType EnumType##FromNSString(NSString *string) \
{ \
ENUM_DEF(ENUM_STRCMP) \
return (EnumType)0; \
} 

Very good macros, you saved a lot of time on my project with this.
However I needed to change

#define ENUM_STRCMP(name,assign) if (![string isEqualToString:@#name]) return name;

to

#define ENUM_STRCMP(name,assign) if ([string isEqualToString:@#name]) return name;

in order to have the EnumType##FromNSString working properly

Cheers

I like the macro approach.
Yet, it can be tricky to debug code generated with macros.
Alternatively, you can generate a table for the conversion.
You can extend the idea of have any arbitrary information per enum.

// enum to string example

define FOR_EACH_GENDER(tbd) \

    tbd(GENDER_MALE) \
    tbd(GENDER_FEMALE) \
    tbd(GENDER_INTERSEX) \

define ONE_GENDER_ENUM(name) name,

enum
{
FOR_EACH_GENDER(ONE_GENDER_ENUM)
MAX_GENDER
};

define ONE_GENDER(name) #name,

static const char *enumGENDER_TO_STRING[] =
{
FOR_EACH_GENDER(ONE_GENDER)
};

// access string name with enumGENDER_TO_STRING[value]
// or, to be safe converting from a untrustworthy caller
static const char *enumGenderToString(unsigned int value)
{
if (value < MAX_GENDER)
{
return enumGENDER_TO_STRING[value];
}
return NULL;
}

static void printAllGenders(void)
{
for (int ii = 0; ii < MAX_GENDER; ii++)
{
printf("%d) gender %s\n", ii, enumGENDER_TO_STRING[ii]);
}
}

//------------------------------------------------------------------------------
// you can assign an arbitrary value and/or information to each enum,

define FOR_EACH_PERSON(tbd) \

    tbd(2, PERSON_FRED,     "Fred",     "Weasley", GENDER_MALE,   12) \
    tbd(4, PERSON_GEORGE,   "George",   "Weasley", GENDER_MALE,   12) \
    tbd(6, PERSON_HARRY,    "Harry",    "Potter",  GENDER_MALE,   10) \
    tbd(8, PERSON_HERMIONE, "Hermione", "Granger", GENDER_FEMALE, 10) \

define ONE_PERSON_ENUM(value, ename, first, last, gender, age) ename = value,

enum
{
FOR_EACH_PERSON(ONE_PERSON_ENUM)
};

typedef struct PersonInfoRec
{
int value;
const char *ename;
const char *first;
const char *last;
int gender;
int age;
} PersonInfo;

define ONE_PERSON_INFO(value, ename, first, last, gender, age) \

                 { ename, #ename, first, last, gender, age },

static const PersonInfo personInfo[] =
{
FOR_EACH_PERSON(ONE_PERSON_INFO)
{ 0, NULL, NULL, NULL, 0, 0 }
};
// note: if the enum values are not sequential, you need another way to lookup
// the information besides personInfo[ENUM_NAME]

static void printAllPersons(void)
{
for (int ii = 0; ; ii++)
{
const PersonInfo *pPI = &personInfo[ii];
if (!pPI->ename)
{
break;
}
printf("%d) enum %-15s %8s %-8s %13s %2d\n",
pPI->value, pPI->ename, pPI->first, pPI->last,
enumGenderToString(pPI->gender), pPI->age);
}
}

hmm.. I was disappointed how github left-justified all my lines of code.
I suggest they improve this as it's common for people to supply code in the replies...

@fredwork you can format your code by putting triple backticks before and after it: https://help.github.com/articles/github-flavored-markdown/#fenced-code-blocks

(The Objective-C language specifier is objc)