How to make constants

How to make constants in Objective-C?

Use define

It’s simple way. Like C, Add define definition in any place.
We usually it to header file(.h)


#define kABC 123
#define kStr @"Const"


Const is C++ prefix. Objective-C also support
The way is a bit interesting.
Add extern in header and also, add



extern const int kABC;
extern NSString * const kStr;


const int kABC = 123;
NSString * const kStr = @"Const";

How to use?

NSLog(@"Const %d", kABC);
NSLog(@"Const %@", kStr);

The use is same.

What’s difference?

What is differences between two?
#define makes new variable(only replace var) every time this is shown up.
extern const is only one var.