Question

I need a array of strings in a constant. is a good idea to use #define?

For example:

#define rows [NSArray arrayWithObjects:  @"NameRowA",@"NameRowB",@"NameRowC", nil]


#define KEY_ROWA [columnas objectAtIndex:0]
#define KEY_ROWB [columnas objectAtIndex:1]
#define KEY_ROWC [columnas objectAtIndex:2]

I need to access to the array of strings and the elements of that array.

I have read, (i don´t know if is true) with this way it is created a new NSArray when it is used, I suppose then the array is released, so I think this is good because you only use that part of memory when you need it.

Answer 1

I don’t think you want to use #define for this.

In your example, there is no constant array of strings made with this code. Every single time rows is used in your code, a new NSArray is going to be allocated. Also, KEY_ROWA refers to columnas, but that isn’t in the rows define. I assume you have something like this

NSArray *columnas = rows;

There is really no difference between that and

NSArray *columnas = [NSArray arrayWithObjects: @"NameRowA",@"NameRowB",@"NameRowC", nil];

But the second line is a lot more obvious. The same is true with KEY_ROWA — the objectAtIndex call would be more obvious and the macro doesn’t get you anything.

I’m not sure what you need exactly, but if you need a shared constant array of strings inside of one class, you could declare it as + instead of - at the beginning, and allocate it once (this is a class variable as opposed to an instance variable). More info here:

How do I declare class-level properties in Objective-C?