how to declare constants in objective c

Question

I need to declare two different constants in my app one is a simple string, the other needs to be a uint32.

I know of two different ways to declare constants as follows

#define VERSION 1; //I am not sure how this works in regards to uint32.. but thats what I need it to be.

and

NSString * const SIGNATURE = @"helloworld";

is there a way to do the version which should be a uint32 like the nsstring decliration below?

for instance something like

UInt32 * const VERSION 1;

if so how? if not, how do i make sure the #define version is of type uint32?

any help would be appreciated

would [this related, potentially duplicate question](http://stackoverflow.com/questions/1674032/static-const-vs-define-in-c) have the answer you're looking for? — Michael Dautermann, Feb 22 '12 at 21:05
possible duplicate of [Constants in Objective C](http://stackoverflow.com/questions/538996/constants-in-objective-c) — Krizz, Feb 22 '12 at 21:07

score 5 · Accepted Answer · answered Feb 22 '12 at 21:07

5

You're very close. The correct syntax is:

const UInt32 VERSION = 1;

You can also use UInt32 const rather than const UInt32. They're identical for scalars. For pointers such as SIGNATURE, however, the order matters, and your order is correct.

answered Feb 22 '12 at 21:07

Rob Napier

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cool, thanks very much for that, I will mark your answer once the time is up for doing so. pretty much that explains why I was getting the pointer error because I was using the *... damn i hate pointers. – C.Johns Feb 22 '12 at 21:09

score 2 · Answer 2 · edited Feb 22 '12 at 21:39

You're confused by macro definitions & constants:

#define VERSION (1)

or

#define SOME_STRING @"Hello there"

The above are macro definitions. This means during compilation VERSION & SOME_STRING will be replaced with the defined values all over the code. This is a quicker solution, but is more difficult to debug.

Examples of constant declarations are:

const NSUInteger VERSION = 1;
NSString * const RKLICURegexException = @"Some string";

Look at the constants like simple variables that are immutable and can't change their values.

Also, be careful with defining pointers to constants & constant values.

how to declare constants in objective c

2 Answers2