Using enum in Objective-C?

Question

Is this the correct (or even a valid way) to use emums in Objective-C? i.e. The menuItem is not used but just defines a list add=1, load=2, list=3 etc.

enum menuItems {
    add = 1    ,
    save       ,
    load       ,
    list       ,
    removeAll  ,
    remove     ,
    quit       
};

int optionSelect;

scanf("%d", &optionSelect);

switch (optionSelect) {
    case add: 
        //...
        break;
}

cheers gary

Added the C tag since you're not doing any Obj-C here. Just to point out that valid C is totally valid within Obj-C. :) — Pascal
– Pascal, Commented Nov 2, 2009 at 17:27

BitDrink · Accepted Answer · 2009-11-02 17:38:04Z

17

If you want to give a semantic meaning to the enumeration, you can consider to define a customized type and declare the variable "optionSelect" as variable of that type! In code...

typedef enum menuItems {
       add = 1,
       save,
       load,
       list,
       removeAll,
       remove,
       quit} MenuItem;


MenuItem optionSelect;

scanf("%d", &optionSelect);

switch (optionSelect) {
    case add: 
    ...
    break;
    .
    .
    .
}

That is, almost, the same thing you have written, but from the side of the developer you give a particular meaning to the variable "optionSelect", not just a simple int!

answered Nov 2, 2009 at 17:38

BitDrink

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1 Comment

BergQuester Over a year ago

Be sure to check out NS_ENUM and NS_OPTIONS. These Apple provided macros take much the guesswork out of writing enums. nshipster.com/ns_enum-ns_options

Tommy · Accepted Answer · 2013-10-05 00:43:07Z

4

In this, the future, it's possibly also helpful to mention NS_ENUM. You'd use it like:

typedef NS_ENUM(uint16_t, TYEnummedType)
{
    TYEnummedType1,
    TYEnummedType2
};

That has almost the same effect as a normal enum and typedef but explicitly dictates the integer type, which is really helpful if you ever want to pack these things off somewhere, be precise in your struct alignment, amongst other uses.

It was added to the iOS SDK with version 6 and OS X with 10.8 but it's just a C macro and doesn't add anything that you couldn't do with vanilla typedef and enum, so there's no backwards compatibility to worry about. It exists only explicitly to tie the two things together.

answered Oct 5, 2013 at 0:43

Tommy

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Comments

Boris Vidolov · Accepted Answer · 2013-10-05 00:30:18Z

1

Your way will work. However, if you would like to use menuItems as a type for variables or parameters, you will need to do a typedef:

typedef enum {add = 1,save,load,list,removeAll,remove,quit}  menuItems;
menuItems m = add;
[myobj passItem:m];

answered Oct 5, 2013 at 0:30

Boris Vidolov

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