enum Values to NSString iOS

Question

I have an enum holding several values   enum  value1  value2  value3   myValue   In a certain point in my app  I wish to check which value of the enum is now active  I m using NSLog but I m not clear on how to display the current value of the enum  value1 valu2 valu3 etc     as a NSString for the NSLog   Anyone

User · Answer

Suppose requirement is to enumerate list of languages.

Add this to .h file

typedef NS_ENUM(NSInteger, AvailableLanguage) {
  ENGLISH,
  GERMAN,
  CHINENSE
};

Now, in .m file simply create an array like,

// Try to use the same naming convention throughout. 
// That is, adding ToString after NS_ENUM name;

NSString* const AvailableLanguageToString[] = {
  [ENGLISH] = @"English",
  [GERMAN]  = @"German",
  [CHINESE] = @"Chinese"
};

Thats it. Now you can use enum with easy and get string for enums using array. For example,

- (void) setPreferredLanguage:(AvailableLanguage)language {
  // this will get the NSString* for the language.
  self.preferredLanguage = AvailableLanguageToString[language];
}

Thus, this pattern depends on accepted naming convention of NS_ENUM and companion ToString array. Try to follow this convention through out and it will become natural.

User · Answer

This is answered here  a few suggestions on implementation  The bottom line is Objective-C is using a regular  old C enum  which is just a glorified set of integers   Given an enum like this   typedef enum   a  b  c   FirstThreeAlpha    Your method would look like this   -  NSString   convertToString  FirstThreeAlpha  whichAlpha       NSString  result   nil       switch whichAlpha            case a              result     a               break          case b              result     b               break          case c              result     c               break           default              result     unknown              return result

User · Answer

Here is a plug-and-play solution that you can extend with a simple copy and paste of your EXISTING definitions   I hope you all find it useful  as I have found useful so many other StackOverflow solutions   -  NSString   enumItemNameForPrefix  NSString  enumPrefix item  int enumItem   NSString  enumList   nil  if   enumPrefix isEqualToString    Add Your Enum Name Here             Instructions         1  leave all code as is  it s good reference and won t conflict         2  add your own enums below as follows            2 1  duplicate the LAST else block below and add as many enums as you like           2 2  Copy then Paste your list  including carraige returns           2 3  add a back slash at the end of each line to concatenate the broken string        3  your are done    else if   enumPrefix isEqualToString   ExampleNonExplicitType          enumList            ExampleNonExplicitTypeNEItemName1        ExampleNonExplicitTypeNEItemName2        ExampleNonExplicitTypeNEItemName3            else if   enumPrefix isEqualToString   ExampleExplicitAssignsType          enumList            ExampleExplicitAssignsTypeEAItemName1   1        ExampleExplicitAssignsTypeEAItemName2   2        ExampleExplicitAssignsTypeEAItemName3   4            else if   enumPrefix isEqualToString    Duplicate and Add Your Enum Name Here  1             Instructions         1  duplicate this else block and add as many enums as you like        2  Paste your list  including carraige returns        3  add a back slash at the end of each line to continue concatenate the broken string     enumList             Replace only this line  Paste your Enum Definition List Here                 parse it int implicitIndex   0  NSString  itemKey   nil  NSString  itemValue   nil  NSArray  enumArray    enumList componentsSeparatedByString        NSMutableDictionary  enumDict      NSMutableDictionary alloc  initWithCapacity enumArray count  autorelease    for  NSString  itemPair in enumArray        NSArray  itemPairArray    itemPair componentsSeparatedByString            itemValue     itemPairArray objectAtIndex 0  stringByTrimmingCharactersInSet  NSCharacterSet whitespaceAndNewlineCharacterSet        itemKey    NSString stringWithFormat    d   implicitIndex       if  itemPairArray count  gt  1          itemKey     itemPairArray lastObject  stringByTrimmingCharactersInSet  NSCharacterSet whitespaceAndNewlineCharacterSet         enumDict setValue itemValue forKey itemKey       implicitIndex          return value with or without prefix NSString  withPrefix    enumDict valueForKey  NSString stringWithFormat    d   enumItem    NSString  withoutPrefix    withPrefix stringByReplacingOccurrencesOfString enumPrefix withString       NSString  outValue    0   withPrefix   withoutPrefix   if  0  NSLog   enum    item  d retVal    dict      enumPrefix  enumItem  outValue  enumDict   return outValue      Here are the example declarations   typedef enum  type1   ExampleNonExplicitTypeNEItemName1   ExampleNonExplicitTypeNEItemName2   ExampleNonExplicitTypeNEItemName3   ExampleNonExplicitType   typedef enum  type2   ExampleExplicitAssignsTypeEAItemName1   1   ExampleExplicitAssignsTypeEAItemName2   2   ExampleExplicitAssignsTypeEAItemName3   4   ExampleExplicitAssignsType    Here is an example call   NSLog   EXAMPLE   type1     type2        self enumItemNameForPrefix   ExampleNonExplicitType  item ExampleNonExplicitTypeNEItemName2    self enumItemNameForPrefix   ExampleExplicitAssignsType  item ExampleExplicitAssignsTypeEAItemName3      Enjoy   -

User · Answer

If I can offer another solution that has the added benefit of type checking  warnings if you are missing an enum value in your conversion  readability  and brevity   For your given example  typedef enum   value1  value2  value3   myValue  you can do this   NSString  NSStringFromMyValue myValue type        const char  c str   0   define PROCESS VAL p  case p   c str    p  break      switch type                PROCESS VAL value1               PROCESS VAL value2               PROCESS VAL value3          undef PROCESS VAL      return  NSString stringWithCString c str encoding NSASCIIStringEncoding         As a side note  It is a better approach to declare your enums as so   typedef NS ENUM NSInteger  MyValue        Value1   0      Value2      Value3     With this you get type-safety  NSInteger in this case   you set the expected enum offset    0

User · Answer

a macro    define stringWithLiteral literal    literal  an enum   typedef NS ENUM NSInteger  EnumType        EnumType0      EnumType1      EnumType2     an array   static NSString   const EnumTypeNames           stringWithLiteral EnumType0       stringWithLiteral EnumType1       stringWithLiteral EnumType2      using   EnumType enumType        NSString  enumName   EnumTypeNames enumType           EDIT       Copy the following code to your project and run    define stringWithLiteral literal    literal  typedef NS ENUM NSInteger  EnumType        EnumType0      EnumType1      EnumType2     static NSString   const EnumTypeNames           stringWithLiteral EnumType0       stringWithLiteral EnumType1       stringWithLiteral EnumType2      -  void test       EnumType enumType   EnumType1      NSString  enumName   EnumTypeNames enumType       NSLog   enumName       enumName

User · Answer

You could use X macros - they are perfect for this   Benefits  1  the relationship between the actual enum value and the string value is in one place   2  you can use regular switch statements later in your code   Detriment  1  The initial setup code is a bit obtuse  and uses fun macros   The code   define X a  b  c  a b  enum ZZObjectType       ZZOBJECTTYPE TABLE    typedef NSUInteger TPObjectType   undef X   define XXOBJECTTYPE TABLE   X ZZObjectTypeZero    0   ZZObjectTypeZero     X ZZObjectTypeOne    1   ZZObjectTypeOne     X ZZObjectTypeTwo    2   ZZObjectTypeTwo     X ZZObjectTypeThree    3   ZZObjectTypeThree         NSString  nameForObjectType  ZZObjectType objectType    define X a  b  c   c   NSNumber numberWithInteger a       NSDictionary  returnValue    NSDictionary dictionaryWithObjectsAndKeys ZZOBJECTTYPE TABLE nil    undef X     return  returnValue objectForKey  NSNumber numberWithInteger objectType          ZZObjectType objectTypeForName  NSString   objectTypeString    define X a  b  c   NSNumber numberWithInteger a    c      NSDictionary  dictionary    NSDictionary dictionaryWithObjectsAndKeys ZZOBJECTSOURCE TABLE nil    undef X     NSUInteger value     NSNumber    dictionary objectForKey objectTypeString  intValue       return  ZZObjectType value      Now you can do   NSString  someString     ZZObjectTypeTwo  ZZObjectType objectType     XXObject objectTypeForName someString  intValue   switch  objectType        case ZZObjectTypeZero                     break      case ZZObjectTypeOne                     break      case ZZObjectTypeTwo                     break      This pattern has been around since the 1960 s  no kidding    http   en wikipedia org wiki X Macro

User · Answer

In some cases when you need to convert enum -  NSString and NSString -  enum it might be simpler to use a typedef and  define  or const NSStrings  instead of enum   typedef NSString          ImageType   define ImageTypeJpg        JPG   define ImageTypePng        PNG   define ImageTypeGif        GIF    and then just operate with  named  strings as with any other NSString    interface MyData   NSObject  property  copy  nonatomic  ImageType imageType   end   implementation MyData -  void doSomething                 self imageType   ImageTypePng                if   self imageType isEqualToString ImageTypeJpg                            end

User · Answer

I found this website  from which the example below is taken  which provides an elegant solution to this problem  The original posting though comes from this StackOverflow answer      Place this in your  h file  outside the  interface block typedef enum       JPG      PNG      GIF      PVR   kImageType   define kImageTypeArray   JPEG     PNG     GIF     PowerVR   nil          Place this in the  m file  inside the  implementation block    A method to convert an enum to string - NSString   imageTypeEnumToString  kImageType enumVal       NSArray  imageTypeArray     NSArray alloc  initWithObjects kImageTypeArray       return  imageTypeArray objectAtIndex enumVal         A method to retrieve the int value from the NSArray of NSStrings - kImageType  imageTypeStringToEnum  NSString  strVal       NSArray  imageTypeArray     NSArray alloc  initWithObjects kImageTypeArray       NSUInteger n    imageTypeArray indexOfObject strVal       if n  lt  1  n   JPG      return  kImageType  n

User · Answer

Below is a example of Enum Struct that is Objective-C friendly in the event you need to use Swift Code in Legacy projects written in Objective-C   Example   contentType filename  toString             returns  filename      contentType filename  rawValue       returns the Int Value  1  since its the second item on struct     objc enum contentType Int          date when content was created  RFC2183      case creationDate        name to be used when creating file     RFC2183      case filename        whether or not processing is required  RFC3204      case handling        date when content was last modified    RFC2183      case modificationDate        original field name in form    RFC7578      case name        Internet media type  and parameters  of the preview output desired from a processor by the author of the MIME content  RFC-ietf-appsawg-text-markdown-12      case previewType        date when content was last read    RFC2183      case readDate        approximate size of content in octets  RFC2183      case size        type or use of audio content   RFC2421      case voice      func toString   - gt  String           switch self           case  creationDate              return  creation-date          case  filename              return  filename          case  handling              return  handling          case  modificationDate              return  modification-date          case  name              return  name          case  previewType              return  preview-type          case  readDate                  return  read-date          case  size              return  size          case  voice              return  voice                   eom    eo-enum

User · Answer

This will be validated by compiler  so you won t mix up indices accidentally  NSDictionary  stateStrings            MCSessionStateNotConnected      quot MCSessionStateNotConnected quot        MCSessionStateConnecting      quot MCSessionStateConnecting quot        MCSessionStateConnected      quot MCSessionStateConnected quot        NSString  stateString    stateStrings objectForKey   state      var stateStrings   MCSessionState  String           notConnected    quot MCSessionState notConnected quot        connecting    quot MCSessionState connecting quot        connected    quot MCSessionState connected quot    var stateString   stateStrings MCSessionState Connected    UPDATE  A more Swifty way is to extend the enum with CustomStringConvertible conformance  Also  this way the compiler will safeguard to implement every new addition to the underlying enum  whereas using arrays does not   as switch statements must be exhaustive  extension MCSessionState  CustomStringConvertible            public var description  String           switch self           case  notConnected              return  quot MCSessionState notConnected quot          case  connecting              return  quot MCSessionState connecting quot          case  connected              return  quot MCSessionState connected quot           unknown default              return  quot Unknown quot                         You can use it like this  var stateString   MCSessionState connected description     Or this  var stateString    quot   MCSessionState connected  quot

User · Answer

This is similar to the  X  macro post by pixel  thanks for the link to http   en wikipedia org wiki X Macro  Code generated in macros can be tricky and hard to debug  Instead  generate a table that is used by  normal  code  I find that many people object to having macros generate code  and may be one reason the technique of  X Macros  as presented in the wiki is not widely adopted   By generating a table  you still need only edit one place to extend the list  and since you can t  step through  a table in the debugger  this removes the objection from many people about multi-lines of code buried in macros     ------------------------------------------------------------------------------    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  lt  MAX GENDER                return enumGENDER TO STRING value             return NULL     static void printAllGenders void        for  int ii   0   ii  lt  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    amp personInfo ii           if   pPI- gt ename                        break                    printf   d  enum  -15s   8s  -8s  13s  2d n               pPI- gt value  pPI- gt ename  pPI- gt first  pPI- gt last              enumGenderToString pPI- gt gender   pPI- gt age

User · Answer

I will introduce is the way I use  and it looks better than previous answer  I thinks   I would like to illustrate with UIImageOrientation for easy understanding   typedef enum       UIImageOrientationUp   0                default orientation  set to 0 so that it always starts from 0     UIImageOrientationDown              180 deg rotation     UIImageOrientationLeft              90 deg CCW     UIImageOrientationRight             90 deg CW     UIImageOrientationUpMirrored        as above but image mirrored along other axis  horizontal flip     UIImageOrientationDownMirrored      horizontal flip     UIImageOrientationLeftMirrored      vertical flip     UIImageOrientationRightMirrored     vertical flip   UIImageOrientation    create a method like   NSString  stringWithUIImageOrientation UIImageOrientation input        NSArray  arr            UIImageOrientationUp                 default orientation       UIImageOrientationDown               180 deg rotation       UIImageOrientationLeft               90 deg CCW       UIImageOrientationRight              90 deg CW       UIImageOrientationUpMirrored         as above but image mirrored along other axis  horizontal flip       UIImageOrientationDownMirrored       horizontal flip       UIImageOrientationLeftMirrored       vertical flip       UIImageOrientationRightMirrored      vertical flip            return  NSString    arr objectAtIndex input       All you have to do is     name your function  copy contents of enum and paste that between NSArray  arr        and       return  NSString    arr objectAtIndex input   put some         and comma PROFIT

User · Answer

I didn t like putting the enum on the heap  without providing a heap function for translation   Here s what I came up with   typedef enum  value1  value2  value3  myValue   define myValueString enum       value1    value2    value3   objectAtIndex enum    This keeps the enum and string declarations close together for easy updating when needed   Now  anywhere in the code  you can use the enum macro like this   myValue aVal   value2  NSLog   The enum value is         myValueString aVal     outputs  The enum value is  value2     To guarantee the element indexes  you can always explicitly declare the start or all  enum values   enum  value1 0  value2 1  value3 2

User · Answer

This is an old question  but if you have a non contiguous enum use a dictionary literal instead of an array   typedef enum       value1   0      value2   1      value3   2          beyond value3     value1000   1000      value1001   MyType    define NSStringFromMyType  value                             value1          value1                value2          value2                value3          value3                value1000       value1000                value1001       value1001                      value

User · Answer

The solution below uses the preprocessor s stringize operator  allowing for a more elegant solution  It lets you define the enum terms in just one place for greater resilience against typos   First  define your enum in the following way     define ENUM TABLE   X ENUM ONE        X ENUM TWO         define X a     a typedef enum Foo       ENUM TABLE   MyFooEnum   undef X   define X a       a NSString   const enumAsString           ENUM TABLE     undef X   Now  use it in the following way      Usage MyFooEnum t   ENUM ONE  NSLog   Enum test - t is       enumAsString t     t   ENUM TWO  NSLog   Enum test - t is now       enumAsString t      which outputs   2014-10-22 13 36 21 344 FooProg 367 60b  Enum test - t is  ENUM ONE 2014-10-22 13 36 21 344 FooProg 367 60b  Enum test - t is now  ENUM TWO    pixel s answer pointed me in the right direction

User · Answer

Here is working code  https   github com ndpiparava ObjcEnumString    1st Approach  define enumString arg       arg     2nd Approach    NSString   secondApproach convertEnumToString  StudentProgressReport status        char  str   calloc sizeof kgood  1  sizeof char        int  goodsASInteger   NSSwapInt  unsigned int kgood       memcpy str   const void   amp goodsASInteger  sizeof goodsASInteger        NSLog    s   str       NSString  enumString    NSString stringWithUTF8String str       free str        return enumString       Third Approcah to enum to string NSString  const kNitin     Nitin   NSString  const kSara     Sara     typedef NS ENUM NSUInteger  Name        NameNitin      NameSara         NSString   thirdApproach convertEnumToString   Name weekday          strong NSString   pointer    NSString     amp kNitin      pointer   weekday      return  pointer

[ios] enum Values to NSString (iOS)

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